[PowerPC][NFC] Reclaim TSFlags bit 6

We removed UseVSXReg flag in https://reviews.llvm.org/D58685
But we did not reclain the bit 6 it was assigned,
this will become confusing and a hole later..
We should reclaim it as early as possible before new bits.

Reviewed By: sfertile

Differential Revision: https://reviews.llvm.org/D72649

llvm/lib/Target/PowerPC/PPCInstrFormats.td

@@ -39,7 +39,7 @@ class I<bits<6> opcode, dag OOL, dag IOL, string asmstr, InstrItinClass itin>
 
   // Indicate that this instruction is of type X-Form Load or Store
   bits<1> XFormMemOp = 0;
-  let TSFlags{7}  = XFormMemOp;
+  let TSFlags{6}  = XFormMemOp;
 
   // Fields used for relation models.
   string BaseName = "";

llvm/lib/Target/PowerPC/PPCInstrInfo.h

@@ -65,7 +65,7 @@ enum {
   NewDef_Shift = 6,
 
   /// This instruction is an X-Form memory operation.
-  XFormMemOp = 0x1 << (NewDef_Shift+1)
+  XFormMemOp = 0x1 << NewDef_Shift
 };
 } // end namespace PPCII