[AArch64] Remove floating-point narrow stores from getUsefulBitsForUse.

While not impossible, it's unlikely we'd be performing bitwise operations on FP
values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269260 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed