[llvm] [AArch64][SVE] Fold ADD+CNTB to INCB and DECB (PR #118280)

[Ricardo Jesus via llvm-commits]

rj-jesus wrote:

I've updated this to fold only the {1, 2, 4} forms of INCB/DECB.

https://github.com/llvm/llvm-project/pull/118280