Reduce dyn_cast<> to isa<> or cast<> where possible.

No functional change intended.

llvm-svn: 234586
diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
index a2209ab..51b79cd 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -2106,7 +2106,7 @@
       // is Big Endian.
       unsigned OpIdx = NElts - i - 1;
       SDValue Operand = BVN->getOperand(OpIdx);
-      if (dyn_cast<ConstantSDNode>(Operand))
+      if (isa<ConstantSDNode>(Operand))
         // This operand is already in ConstVal.
         continue;