dm mpath: move trigger_event member to the end of 'struct multipath'

Allows the 'work_mutex' member to no longer cross a cacheline.

Reviewed-by: Hannes Reinecke <[e-mail]>
Tested-by: Hannes Reinecke <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-mpath.c

···
 	atomic_t pg_init_in_progress;	/* Only one pg_init allowed at once */
 	atomic_t pg_init_count;		/* Number of times pg_init called */
 
-	struct work_struct trigger_event;
-
 	/*
 	 * We must use a mempool of dm_mpath_io structs so that we
 	 * can resubmit bios on error.
···
 	mempool_t *mpio_pool;
 
 	struct mutex work_mutex;
+	struct work_struct trigger_event;
 };
 
 /*