Fix a use of LLVM_FALLTHROUGH that wasn't even in a switch.

I was over-aggressive in my conversions from comments to the
fallthrough attribute.

llvm-svn: 278903

llvm/lib/TableGen/TGParser.cpp

@@ -1286,7 +1286,6 @@ Init *TGParser::ParseSimpleValue(Record *CurRec, RecTy *ItemType,
           continue;
         }
         // Fallthrough to try convert this to a bit.
-        LLVM_FALLTHROUGH;
       }
       // All other values must be convertible to just a single bit.
       Init *Bit = Vals[i]->convertInitializerTo(BitRecTy::get());