[mips][microMIPS] Implement PRECEQ.W.PHL, PRECEQ.W.PHR, PRECEQU.PH.QBL,...

[mips][microMIPS] Implement PRECEQ.W.PHL, PRECEQ.W.PHR, PRECEQU.PH.QBL, PRECEQU.PH.QBLA, PRECEQU.PH.QBR, PRECEQU.PH.QBRA, PRECEU.PH.QBL, PRECEU.PH.QBLA, PRECEU.PH.QBR and PRECEU.PH.QBRA instructions
Differential Revision: http://reviews.llvm.org/D14279

llvm-svn: 253326