[media] coda: use vb2_set_plane_payload instead of setting v4l2_planes[0].bytesused directly

As stated in the vb2_buffer documentation, drivers should not directly fill
in v4l2_planes[0].bytesused, but should use the vb2_set_plane_payload()
function instead. No functional changes.

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