Use COPY_TO_REGCLASS instead of pseudo instructions for Neon FP patterns.

Use COPY_TO_REGCLASS instead of pseudo instructions for Neon FP patterns.
Jakob Olesen suggested that we can avoid the need for separate pseudo
instructions here by using COPY_TO_REGCLASS in the patterns.  The pattern
gets pretty ugly but it seems to work well.  Partial fix for Radar 8711675.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121718 91177308-0d34-0410-b5e6-96231b3b80d8