[arm] Rename Tag_VFP_arch to Tag_FP_arch.

According to "Addenda to ABI for ARM architecture", Tag_FP_arch is the
new name for the equivalent Tag_VFP_arch.  This commit renames
Tag_VFP_arch to Tag_FP_arch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197587 91177308-0d34-0410-b5e6-96231b3b80d8