ltr502als.c: Port patches from GB

ltr502als.c: Port patches from GB

BZ: 17031

This patch inclues fixing for the following bugs:
BZ 16176: Obviate incorrect PS interrupt
BZ 13626: Reduce intergation circles and enhance adc-lux conversion
BZ 10605: workaround for proximity sensor do not work on first boot issue
BZ 13733: Add GPL header in the code file

Change-Id: I81b73662115d421d7a002a79d096e8a87590ec4a
Signed-off-by: Leo Yan <leo.yan@intel.com>
Reviewed-on: http://android.intel.com:8080/27132
Reviewed-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: Du, Alek <alek.du@intel.com>
Reviewed-by: Koskinen, Ilkka <ilkka.koskinen@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>