[mips] Print move instructions.

"move $4, $5" is printed instead of "or $4, $5, $zero".



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176455 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/Mips/frame-address.ll

@@ -8,5 +8,5 @@ entry:
   ret i8* %0
 
 ; CHECK:   move    $fp, $sp
-; CHECK:   or    $2, $fp, $zero
+; CHECK:   move    $2, $fp
 }