Mips assembler: Explicit floating point condition register recognition.

This patch allows the assembler to recognize $fcc0 
as a valid register for conditional move instructions. 

Corresponding test cases have been added.

Contributer: Vladimir Medic



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179567 91177308-0d34-0410-b5e6-96231b3b80d8