ARM: Fix fastcc calling convention for Thumb1

When targetting Thumb1 on a processor which has a VFP unit (which
is not accessible from Thumb1), we were converting the fastcc calling
convention to AAPCS-VFP, which is not possible.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210889 91177308-0d34-0410-b5e6-96231b3b80d8