Fix pattern for memory form of PSHUFD for use with FP vectors to remove bitcast to...

Fix pattern for memory form of PSHUFD for use with FP vectors to remove bitcast to an integer vector that normal code wouldn't have. Also remove bitcasts from code that turns splat vector loads into a shuffle as it was making the broken pattern necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149232 91177308-0d34-0410-b5e6-96231b3b80d8