[mips][msa] Added support for matching splati from normal IR (i.e. not intrinsics)

Updated some of the vshf since they (correctly) emit splati's now



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191511 91177308-0d34-0410-b5e6-96231b3b80d8