[ARM] Allow CMPZ transforms even if the input has multiple uses.

It looks like this got left in by accident in r289794; I can't think of
any reason this check would be necessary.  (Maybe it was meant to be a
check that the AND has one use? But we check that a few lines earlier.)

Differential Revision: https://reviews.llvm.org/D47921

llvm-svn: 334322