V4L/DVB (8838): CRED: Wrap task credential accesses in video input drivers

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cpia.c

@@ -3202,7 +3202,7 @@ static int cpia_open(struct inode *inode, struct file *file)
 
 	/* Set ownership of /proc/cpia/videoX to current user */
 	if(cam->proc_entry)
-		cam->proc_entry->uid = current->uid;
+		cam->proc_entry->uid = current_uid();
 
 	/* set mark for loading first frame uncompressed */
 	cam->first_frame = 1;