[mips] Addition of the immediate cases for the instructions [d]div, [d]divu

Related to http://reviews.llvm.org/D15772

Depends on http://reviews.llvm.org/D16888

Adds support for immediate operand for [D]DIV[U] instructions.

Patch By: Srdjan Obucina

Reviewers: zoran.jovanovic, vkalintiris, dsanders, obucina

Differential Revision: https://reviews.llvm.org/D16889

llvm-svn: 293614