[Calyx] Fix unnecessary trailing semicolon, NFC

Drop an unnecessary trailing semicolon that was producing a compiler
warning.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>

include/circt/Dialect/Calyx/CalyxLoweringUtils.h

@@ -851,7 +851,7 @@ Type toBitVector(T type) {
     return IntegerType::get(type.getContext(), bitWidth);
   }
   return type;
-};
+}
 
 } // namespace calyx
 } // namespace circt