Add a V4L2 sub-device driver for Hynix Hi-556 image sensor.
This is a camera sensor using the I2C bus for control and the
CSI-2 bus for data.

This driver supports following features:
- manual exposure and analog/digital gain control support
- vblank/hblank control support
- test pattern support
- media controller support
- runtime PM support
- support following resolutions:
  + 2592x1944 at 30FPS
  + 1296x972  at 30FPS

[sakari.ailus@linux.intel.com: Remove MEDIA_CAMERA_SUPPORT from Kconfig dependencies]
Signed-off-by: Shawn Tu <shawnx.tu@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>