Add v4l2_fwnode_parse_reference_sensor_common for parsing common
sensor properties that refer to adjacent devices such as flash or lens
driver chips.

As this is an association only, there's little a regular driver needs to
know about these devices as such.
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Acked-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NSebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>