[DAG] SimplifySetCC - relax fold (X^C1) == C2 --> X == C1^C2

https://alive2.llvm.org/ce/z/A_auBq

Remove limitation that wouldn't perform the fold if all the inverted bits are known zero

The thumb2 changes look to be benign, although it does show that the TEQ/TST isel patterns could probably be improved.

Fixes movmsk regression in D122754

Differential Revision: https://reviews.llvm.org/D123023