[media] coda: bump maximum number of internal framebuffers to 17

The h.264 standard allows up to 16 reference frame for the high profile
and we need one additional internal framebuffer when the VDOA is in use.

Lift the current maximum of 8 internal framebuffers to allow playback
of those video streams.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>