media: ov5640: Add RGB565_1X16 format

The driver already supports the 2X8_[LE|BE] variants of RGB565
formats.

As for CSI-2 the 2X8 variants do not apply, add RGB565_1X16 variant
with little-endian ordering of components as required by the CSI-2
specifications.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>