[media] coda: prefix v4l2_ioctl_ops with coda_ instead of vidioc_

Moving the ioctl handler callbacks into the coda namespace helps
tremendously to make sense of backtraces.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
[k.debski@samsung.com: fix whitespace error near coda_subscribe_event]
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>