[mips][mips64r6] t(eq|ge|lt|ne)i and t(ge|lt)iu are not available in MIPS32r6/MIPS64r6

Summary: Depends on D3872

Reviewers: jkolek, zoran.jovanovic, vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3891