libcamera: Remove unneeded semicolons

Comply with the coding style by removing lots of unneeded semicolons.
Fix a few other coding style violations on the lines touched by those
fixes.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/message.cpp

@@ -161,4 +161,4 @@ void InvokeMessage::invoke()
  * \brief The packed method invocation arguments
  */
 
-}; /* namespace libcamera */
+} /* namespace libcamera */