[media] ov2640: add support for V4L2_MBUS_FMT_YUYV8_2X8, V4L2_MBUS_FMT_RGB565_2X8_BE

This is the result of experimenting with the SpeedLink VAD Laplace webcam.
The register sequence for V4L2_MBUS_FMT_YUYV8_2X8 has been identified by
analyzing USB-logs of this device running on MS Windows.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>