s5k5baf: add camera sensor driver

s5k5baf: add camera sensor driver

Driver for Samsung S5K5BAF UXGA 1/5" 2M CMOS Image Sensor with embedded
SoC ISP. The driver exposes the sensor as two V4L2 subdevices:

- S5K5BAF-CIS - pure CMOS Image Sensor, fixed 1600x1200 format,
  no controls.
- S5K5BAF-ISP - Image Signal Processor, formats up to 1600x1200,
  pre/post ISP cropping, downscaling via selection API, controls.

The private V4L2_CID_{RED/GREEN/BLUE}_GAIN controls will be replaced
with V4L2_CID_{RED/BLUE}_BALANCE controls in subsequent patch.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
v3:
- narrowed state->error usage to i2c and power errors

v2:
- lower-cased driver name,
- removed underscore from regulator names,
- removed platform data code,
- v4l controls grouped in anonymous structs,
- added s5k5baf_clear_error function,
- private controls definitions moved to uapi header file,
- added v4l2-controls.h reservation for private controls,
- corrected subdev registered/unregistered code,
- .log_status sudbev op set to v4l2 helper,
- moved entity link creation to probe routines,
- added cleanup on error to probe function.