[mips] Fix the definition of sync, synci

Also, fix the disassembly of synci for microMIPS.

Reviewers: abeserminji, smaksimovic, atanasyan

Differential Revision: https://reviews.llvm.org/D45870


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330810 91177308-0d34-0410-b5e6-96231b3b80d8
15 files changed