[media] em28xx: add support for Terratec Grabby REC button

Terratec Grabby (hw rev 2) REC button uses the standard snapshot button
configuration.
Signed-off-by: NMatthieu Rogez <matthieu.rogez@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -2015,6 +2015,7 @@ struct em28xx_board em28xx_boards[] = {
 			.vmux     = SAA7115_SVIDEO3,
 			.amux     = EM28XX_AMUX_LINE_IN,
 		} },
+		.buttons         = std_snapshot_button,
 	},
 	[EM2860_BOARD_TERRATEC_AV350] = {
 		.name            = "Terratec AV350",