feat(rt): add initial code for T-Head C907 (Allwinner V861/V881) support

Signed-off-by: Zhouqi Jiang <[email protected]>

Author: luojia65

allwinner-rt/src/arch/thead_c907.rs

@@ -0,0 +1,4 @@
+//! T-Head C907 microarchitecture support.
+
+// TODO thead_c907_start
+// TODO thead_c907_halt

allwinner-rt/src/lib.rs

@@ -33,6 +33,7 @@ pub mod arch {
     pub mod andes_a27l2;
     pub mod riscv_fpu;
     pub mod thead_c906;
+    pub mod thead_c907;
 }
 
 pub mod soc {