media: v4l2-cci: Add support for little-endian encoded registers

Some sensors, e.g. Sony IMX290, are using little-endian registers. Add
support for those by encoding the endianness into Bit 20 of the register
address.

Fixes: af73323b ("media: imx290: Convert to new CCI register access helpers")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[Sakari Ailus: Fixed commit message.]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>