staging: bcm2835_camera: Convert control_service field of mmal_msg_header to u32

The camera driver passes messages back and forth between the firmware with
requests and replies.  One of the fields of the message header called
control_service is a pointer so the size changes between 32 bit and 64 bit.

Luckly, the field is not interperated by the driver, so it can be changed
to a u32 which has a fixed size.
Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/bcm2835-camera/mmal-msg.h

@@ -84,7 +84,7 @@ struct mmal_msg_header {
 	u32 type; /** enum mmal_msg_type */
 
 	/* Opaque handle to the control service */
-	struct mmal_control_service *control_service;
+	u32 control_service;
 
 	struct mmal_msg_context *context; /** a u32 per message context */
 	u32 status; /** The status of the vchiq operation */