LCD_KCAL: Color control driver for OPPO-8974

/sys/devices/platform/kcal_ctrl.0/kcal
/sys/devices/platform/kcal_ctrl.0/kcal_ctrl
/sys/devices/platform/kcal_ctrl.0/kcal_min

kcal:
Write RGB lut data from sysfs. Default values are '255/255/255', send
RGB info 'x x x' to kcal, and send '1' to kcal_ctrl to apply the value
and update the lut info.

kcal_min:
Lower values such as 0-10 ultimately create a dark, washed out display,
if a user accidently sets their kcal values to "0 0 0" they will loose
visual control of the device, potentially requiring a hard reboot.
Introduce minimum kcal values to prevent this behavior. kcal_min will
detect and block values attempting to set lower than itself, resetting
the specific values to that of kcal_min. There is also behavior to
adjust the kcal if kcal_min is set to a level higher than that of any
kcal value(s).

Change-Id: Ib6770d671322440ba26b78ade27e39d1dd3ed889