[fixup] Simplify code

Change-Id: I0e51f00113d0692d5d3751c89eac8167511d1d9e

Author: momchil-velikov

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -15772,12 +15772,9 @@ static bool createTblShuffleMask(unsigned SrcWidth, unsigned DstWidth,
   Mask.resize(MaskLen, NumElts);
 
   unsigned SrcIndex = 0;
-  for (unsigned I = 0; I < MaskLen; I += Factor)
+  for (unsigned I = IsLittleEndian ? 0 : Factor - 1; I < MaskLen; I += Factor)
     Mask[I] = SrcIndex++;
 
-  if (!IsLittleEndian)
-    std::rotate(Mask.rbegin(), Mask.rbegin() + Factor - 1, Mask.rend());
-
   return true;
 }