gpu: ipu-v3: csi: pass back mbus_code_to_bus_cfg error codes

[ Upstream commit d36d0e6309dd8137cf438cbb680e72eb63c81425 ]

mbus_code_to_bus_cfg() can fail on unknown mbus codes; pass back the
error to the caller.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
[p.zabel@pengutronix.de - renamed rc to ret for consistency]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>