[RISCV] Add test case for CASE_VFMA_CHANGE_OPCODE_VV to handle MF4 pseudos (#88947)

The fix was committed in
https://github.com/llvm/llvm-project/commit/8cee94e989b5bf6fb6455087d48eb6c6e0e23c54.
This adds a test.

GitOrigin-RevId: e6ee191f968c1dc39410bcb0db3ee62f51c7d158
1 file changed