Recommit: "[mips] Add rsqrt, recip for MIPS"

Add rsqrt.[ds], recip.[ds] for MIPS. Correct the microMIPS definitions for
architecture support and register usage.

Reviewers: vkalintiris, zoran.jovanoic

Differential Review: https://reviews.llvm.org/D24499

llvm-svn: 283334
58 files changed