[InstCombine] Remove one use restriction on the shift for calls to foldICmpAndShift.

If this transformation succeeds, we're going to remove our dependency on the shift by rewriting the and. So it doesn't matter how many uses the shift has.

This distributes the one use check to other transforms in foldICmpAndConstConst that do need it.

Differential Revision: https://reviews.llvm.org/D38206

llvm-svn: 314233