[llvm] [AMDGPU] Add known bits for G_AMDGPU_COPY_SCC_VCC (PR #180560)

[Petar Avramovic via llvm-commits]

https://github.com/petar-avramovic approved this pull request.

should rebase your vangthao95:globalisel-known-bits-copy-scc-vcc branch, not merge

https://github.com/llvm/llvm-project/pull/180560