[llvm] [RISCV][GlobalISel] Fix selectShiftMask when shift mask is created from G_AND (PR #89602)

[Hongbin Jin via llvm-commits]

bvlgah wrote:

@michaelmaitland Hi Michael, could please help me with merging the patch (I have no write permission), thanks.
One thing to note is I have committed several fix-ups, so squash is needed

https://github.com/llvm/llvm-project/pull/89602