The RenderMethod field in RegisterOperand class sets the name of the method on the target specific operand to call to add the target specific operand to an MCInst. This patch defines RenderMethod for mips RegisterOperand classes and removes redundant code from MipsAsmParser.cpp

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184292 91177308-0d34-0410-b5e6-96231b3b80d8