media: staging: imx: request mbus_config in csi_start

media: staging: imx: request mbus_config in csi_start

Request the upstream mbus_config in csi_start, which starts the stream,
instead of caching it in link_validate.

This allows to get rid of the mbus_cfg field in the struct csi_priv and
avoids state in the driver.

Fixes: 4a34ec8e470c ("[media] media: imx: Add CSI subdev driver")
Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>