[mips] Fix MipsAsmParser::parseCCRRegs.

Enable parsing all 32 floating point control registers $0-31 and stop trying to
parse floating point condition code register $fcc0. Also, return ParseFail if
the operand being parsed is not in the expected format. 



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186861 91177308-0d34-0410-b5e6-96231b3b80d8