[media] em28xx: move v4l2 dummy clock deregistration from the core to the v4l extension

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --cc drivers/media/usb/em28xx/em28xx-cards.c
Simple merge

diff --cc drivers/media/usb/em28xx/em28xx-video.c
Simple merge