[media] ov13858: add support for OV13858 sensor

This patch adds driver for Omnivision's ov13858
sensor, the driver supports following features:

- manual exposure/gain(analog and digital) control support
- two link frequencies
- VBLANK/HBLANK support
- test pattern support
- media controller support
- runtime pm support
- supported resolutions
  + 4224x3136 at 30FPS
  + 2112x1568 at 30FPS(default) and 60FPS
  + 2112x1188 at 30FPS(default) and 60FPS
  + 1056x784 at 30FPS(default) and 60FPS

[Sakari Ailus: use V4L2_CID_DIGITAL_GAIN instead, add MAINTAINERS entry.]

Signed-off-by: Hyungwoo Yang <hyungwoo.yang@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>