Generated C header missing instructions with new subtype schema

[jordancarlin]

Describe the bug
All instructions that have been migrated to use the new type/subtype encoding schema are skipped by generator.py, which is used to produce both the c_header and golang outputs. The resulting files are missing both the MATCH and MASK clauses for these instructions.

To Reproduce
Steps to reproduce the behavior:

1. Run ./do gen:c_header

Text output/Error Messages

⬢ [podman] ❯ ./do gen:c_header
Using devcontainer environment
Running with 1 job(s)
/workspaces/riscv-unified-db/.home/.venv/bin/python3 /workspaces/riscv-unified-db/backends/generators/c_header/generate_encoding.py --inst-dir=/workspaces/riscv-unified-db/gen/resolved_spec/_/inst --csr-dir=/workspaces/riscv-unified-db/gen/resolved_spec/_/csr --ext-dir=/workspaces/riscv-unified-db/gen/resolved_spec/_/ext --output=/workspaces/riscv-unified-db/gen/c_header/encoding.out.h --include-all
INFO:: Loading instructions from /workspaces/riscv-unified-db/gen/resolved_spec/_/inst
INFO:: Searching for instruction files in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst for target architecture BOTH
ERROR:: Missing 'encoding' field in instruction orn in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/orn.yaml
ERROR:: Missing 'encoding' field in instruction andn in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/andn.yaml
ERROR:: Missing 'encoding' field in instruction ror in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/ror.yaml
ERROR:: Missing 'encoding' field in instruction clmulh in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/clmulh.yaml
ERROR:: Missing 'encoding' field in instruction xnor in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/xnor.yaml
ERROR:: Missing 'encoding' field in instruction rorw in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/rorw.yaml
ERROR:: Missing 'encoding' field in instruction rolw in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/rolw.yaml
ERROR:: Missing 'encoding' field in instruction clmul in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/clmul.yaml
ERROR:: Missing 'encoding' field in instruction rol in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/B/rol.yaml
ERROR:: Missing 'encoding' field in instruction add.uw in /workspaces/riscv-unified-db/gen/resolved_spec/_/inst/Zba/add.uw.yaml
INFO:: Found 1150 instruction definitions in 1150 files
INFO:: Filtered out 10 instructions due to encoding issues

Additional context
generator.py is looking specifically for an encoding field, which no longer exists in these instructions. It needs a new way to retrieve the encoding.

There should probably be golden reference files for these artifacts (similar to what is already done for the instruction appendix) to prevent inadvertent issues like these. Or at least a check in CI for error messages.

[omsuneri]

assign me please @jordancarlin