[mips] Correct the predicates of arithmetic and logic instructions.

As part of this effort, duplicate and correct the predicates of some
aliases. Also disable code generation of some short form instructions
for FastISel, as it would otherwise reject them.

Reviewers: atanasyan, abeserminji, smaksimovic

Differential Revision: https://reviews.llvm.org/D47075

llvm-svn: 333530