[media] coda: fix ENC_SEQ_OPTION for CODA7

GAMMA_OFFSET is different between CodaDx6 and CODA7.
Also, this is a bitfield.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>