[SDAG] expand more is-power-of-2 patterns that use popcount

(ctpop x) == 1 --> (x != 0) && ((x & x-1) == 0)

Adjust the legality check to avoid the poor codegen on AArch64.
We probably only want to use popcount on this pattern when it
is a single instruction.

fixes #57225

Differential Revision: https://reviews.llvm.org/D132237