[AMDGPU] Add v_pk_mov_b32 to supported list of unpackable instructions

https://github.com/llvm/llvm-project/commit/c256966fe2129ef75c76a4cab454b35ffa9410f3 added some baseline functionality to unpack v_pk instructions -- by unpacking we are able to co-execute with MFMA. However, we did not support unpacking for all relevant instructions. The remaining instruction is v_pk_mov_b32

Start by reviewing commit c256966fe2129ef75c76a4cab454b35ffa9410f3 and trace the existing v_pk instruction unpacking support. Find the supported-instruction list and add v_pk_mov_b32 there; done means it can be unpacked for co-execution with MFMA and the relevant compiler tests pass.

Written by the indexing model from the issue text.