media: ov2680: Add Omnivision OV2680 sensor driver

This patch adds V4L2 sub-device driver for OV2680 image sensor.
The OV2680 is a 1/5" CMOS color sensor from Omnivision.
Supports output format: 10-bit Raw RGB.
The OV2680 has a single lane MIPI interface.

The driver exposes following V4L2 controls:
- auto/manual exposure,
- exposure,
- auto/manual gain,
- gain,
- horizontal/vertical flip,
- test pattern menu.
Supported resolution are only: QUXGA, 720P, UXGA.

[Sakari Ailus: Drop "-level" from Kconfig help text]

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>