[NFC][MC][Decoder] Fix off-by-one indendation in generated code

Author: jurahul

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -2081,7 +2081,7 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
   OS << ") {\n";
   if (HasCheckPredicate)
     OS << "  const FeatureBitset &Bits = STI.getFeatureBits();\n";
-  OS << "   using namespace llvm::MCD;\n";
+  OS << "  using namespace llvm::MCD;\n";
 
   OS << R"(
   const uint8_t *Ptr = DecodeTable;