Fix build errors due to missing Kconfig dependency.

drivers/built-in.o: In function `sur40_disconnect':
sur40.c:(.text+0x22be6e): undefined reference to `video_unregister_device'
sur40.c:(.text+0x22be77): undefined reference to `v4l2_device_unregister'
drivers/built-in.o: In function `sur40_process_video':
sur40.c:(.text+0x22c1d4): undefined reference to `v4l2_get_timestamp'
drivers/built-in.o: In function `sur40_probe':
sur40.c:(.text+0x22ca82): undefined reference to `v4l2_device_register'
sur40.c:(.text+0x22cb1a): undefined reference to `v4l2_device_unregister'
sur40.c:(.text+0x22cbf7): undefined reference to `video_device_release_empty'
sur40.c:(.text+0x22cc53): undefined reference to `__video_register_device'
sur40.c:(.text+0x22cc90): undefined reference to `video_unregister_device'
drivers/built-in.o: In function `sur40_vidioc_querycap':
sur40.c:(.text+0x22ccb0): undefined reference to `video_devdata'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>