Replace MachineInstr* with MachineInstr& in TargetInstrInfo, NFC

There were a few cases introduced with the modulo scheduler.

llvm-svn: 277358
diff --git a/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp b/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp
index 2f19120..8fc4d95 100644
--- a/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp
@@ -670,7 +670,7 @@
     assert(COpc);
     MachineInstrBuilder MIB = BuildMI(*ToB, At, DL, HII->get(COpc));
     MIOperands MO(*MI);
-    if (HII->isPostIncrement(MI)) {
+    if (HII->isPostIncrement(*MI)) {
       MIB.addOperand(*MO);
       ++MO;
     }