fix a bunch of partially ambiguous patterns on ARM. As an

example, this:

(set DPR:$dst, (fsub (fneg (fmul DPR:$a, DPR:$b)), DPR:$dstin))

is ambiguous because DPR contains both f64 and v2f32.  tblgen
currently accidentally picks f64 because it's first in the 
regclass.

llvm-svn: 97955