[llvm] [AMDGPU] Enable copy from VCC to SHARED_BASE. (PR #164138)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I don't think `s_mov_b64` would allow `SRC_SHARED_BASE` as destination. It is not one of the categories in `sdst`.

Then the instruction definitions are wrong, because this should fail the verifier if it's not valid 

https://github.com/llvm/llvm-project/pull/164138