media: coda: disable encoder cmd ioctl on decoder and vice versa

Use v4l2_disable_ioctl() to disable the VIDIOC_TRY_ENCODER_CMD and
VIDIOC_ENCODER_CMD ioctls on decoder video devices and the
VIDIOC_TRY_DECODER_CMD and VIDIOC_DECODER_CMD ioctls on encoder
video devices.

This allows to drop the coda_try_encoder/decoder_cmd() functions
and to use v4l2_m2m_ioctl_try_encoder/decoder_cmd() directly.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>