[InstSimplify] simplify power-of-2 (single bit set) sequences

As discussed in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314

Improving the canonicalization for these patterns:
rL363956
...means we should adjust/enhance the related simplification.

https://rise4fun.com/Alive/w1cp

  Name: isPow2 or zero
  %x = and i32 %xx, 2048
  %a = add i32 %x, -1
  %r = and i32 %a, %x
  =>
  %r = i32 0

llvm-svn: 363997