ENGR00139383-2 Add ISL29023 light sensor support

ENGR00139383-2 Add ISL29023 light sensor support

This patch adds ISL29023 light sensor support.
Users may control the light sensor work at
different modes/ranges/resolutions or read
the lux value via sysfs.
A power state node is also created in sysfs.
If the light sensor works at ALS once mode,
users need to power down/power up the sensor
before read the lux value again.
Currently, IR(Infra Red) mode is not supported.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>