drivers/misc/isl29020.c: ambient light sensor

The LS driver will read the latest Lux measurement based upon the light
brightness and will report the LUX output through sysfs interface.

This hardware isn't quite the same as the ISL29003 so has a different
driver.

[akpm@linux-foundation.org: put PM code under #ifdef CONFIG_PM]
Signed-off-by: Kalhan Trisal <kalhan.trisal@intel.com>
[Runtime power management support added]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
[Fixes to runtime PM]
Signed-off-by: Liu Hong <hong.liu@intel.com>
[Cleanups and added checks for I2C errors, reworked the API to match the
 saner one agreed for other sensors]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>