[BLAS][rocblas] PI header includes to applies for only DPC++ compiler

[abagusetty]

Description

1. Removes preprocessor macro on pi.hpp which only applies to DPC++ compiler but not to AdaptiveCPP. This logic is already handled under backends/rocblas/rocblas_scope_handle.hpp which is specific to DPC++ and the respective AdaptiveCPP header is already clean backends/rocblas/rocblas_scope_handle_hipsycl.hpp

2. Fixed a deprecated header warning for CL/sycl.hpp and placed it under guards.

Fixes #684

Checklist

All Submissions

• Do all unit tests pass locally? Attach a log.

New interfaces

• Have you provided motivation for adding a new feature as part of RFC and
  it was accepted? # (RFC)
• What version of oneAPI spec the interface is targeted?
• Complete New features checklist

New features

• Have you provided motivation for adding a new feature?
• Have you added relevant tests?

Bug fixes

• Have you added relevant regression tests?
• Have you included information on how to reproduce the issue (either in a
  GitHub issue or in this PR)?

[Rbiessy]

/intelci: run

[andrewtbarker]

Do tests that use the rocblas backend pass?

[abagusetty]

@andrewtbarker @Rbiessy Not sure if I am launching all the tests

$ ctest --verbose
UpdateCTestConfiguration  from :/lustre/orion/csc613/scratch/abagusetty/SYCL_compilers_05282025/abagusetty-onemath/build-acpp-rocm6.4.0/DartConfiguration.tcl
UpdateCTestConfiguration  from :/lustre/orion/csc613/scratch/abagusetty/SYCL_compilers_05282025/abagusetty-onemath/build-acpp-rocm6.4.0/DartConfiguration.tcl
Test project /lustre/orion/csc613/scratch/abagusetty/SYCL_compilers_05282025/abagusetty-onemath/build-acpp-rocm6.4.0
Constructing a list of tests
Done constructing a list of tests
Updating test list for fixtures
Added 0 tests to meet fixture requirements
Checking test dependency graph...
Checking test dependency graph end
test 1
    Start 1: blas/EXAMPLE/RT/gemm_usm/hip:gpu

1: Test command: /lustre/orion/csc613/scratch/abagusetty/SYCL_compilers_05282025/abagusetty-onemath/build-acpp-rocm6.4.0/bin/example_blas_gemm_usm
1: Working Directory: /lustre/orion/csc613/scratch/abagusetty/SYCL_compilers_05282025/abagusetty-onemath/build-acpp-rocm6.4.0/examples/blas/run_time_dispatching/level3
1: Environment variables: 
1:  ONEAPI_DEVICE_SELECTOR=hip:gpu
1: Test timeout computed to be: 10000000
1: 
1: ########################################################################
1: # General Matrix-Matrix Multiplication using Unified Shared Memory Example: 
1: # 
1: # C = alpha * A * B + beta * C
1: # 
1: # where A, B and C are general dense matrices and alpha, beta are
1: # floating point type precision scalars.
1: # 
1: # Using apis:
1: #   gemm
1: # 
1: # Using single precision (float) data type
1: # 
1: # Device will be selected during runtime.
1: # The environment variable ONEAPI_DEVICE_SELECTOR can be used to specify
1: # available devices
1: # 
1: ########################################################################
1: 
1: Running BLAS GEMM USM example on GPU device.
1: Device name is: AMD Instinct MI250X
1: Running with single precision real data type:
1: 
1: 		GEMM parameters:
1: 			transA = trans, transB = nontrans
1: 			m = 45, n = 98, k = 67
1: 			lda = 103, ldB = 105, ldC = 106
1: 			alpha = 2, beta = 3
1: 
1: 		Outputting 2x2 block of A,B,C matrices:
1: 
1: 			A = [ 0.340188, 0.260249, ...
1: 			    [ -0.105617, 0.0125354, ...
1: 			    [ ...
1: 
1: 
1: 			B = [ -0.326421, -0.192968, ...
1: 			    [ 0.363891, 0.251295, ...
1: 			    [ ...
1: 
1: 
1: 			C = [ 0.00698781, 0.525862, ...
1: 			    [ 0.585167, 1.59017, ...
1: 			    [ ...
1: 
1: BLAS GEMM USM example ran OK.
1/1 Test #1: blas/EXAMPLE/RT/gemm_usm/hip:gpu ...   Passed    3.07 sec

100% tests passed, 0 tests failed out of 1

Total Test time (real) =   3.08 sec

[andrewtbarker]

For these small changes I'm happy to see one AMD gpu / rocblas test pass, thanks!