HID: hid-multitouch: remove unused mt_application::dev_time

dev_time was moved to struct mt_application in commit f146d1c4 (HID:
multitouch: Store per collection multitouch data), but is not used since
then. Remove it.

Found by https://github.com/jirislaby/clang-struct.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

drivers/hid/hid-multitouch.c

@@ -130,7 +130,6 @@ struct mt_application {
 				 * > 1 means hybrid (multitouch) protocol
 				 */
 
-	__s32 dev_time;		/* the scan time provided by the device */
 	unsigned long jiffies;	/* the frame's jiffies */
 	int timestamp;		/* the timestamp to be sent */
 	int prev_scantime;		/* scantime reported previously */