[llvm] [AArch64] Fold vector select with power-of-2 bit-test to CMTST+BSP (PR #209100)

[Mugundan S via llvm-commits]

MGN-GIT wrote:

Its been a week, pinging an ARM experts @davemgreen @efriedma-quic to take a look on this PR. 

https://github.com/llvm/llvm-project/pull/209100