media: ov5640: fix virtual_channel parameter permissions

Fix module_param(virtual_channel) permissions.
This problem was detected by checkpatch:
$ scripts/checkpatch.pl -f drivers/media/i2c/ov5640.c
ERROR: Use 4 digit octal (0777) not decimal permissions
+module_param(virtual_channel, int, 0);

Also add an error trace in case of virtual_channel not in
the valid range of values.

Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>