gpadc: enable GPADC on Clovertrail

gpadc: enable GPADC on Clovertrail

BZ: 21885

Platform device creation is handled by the MSIC MFD driver, add
Clovertrail support to mrst.c. The adc driver is changed since
GSM pulse mode is no longer supported on Clovertrail.

Change-Id: I933810065a42305d0c4aa5029db8a94fb6aed4eb
Signed-off-by: Li, Ning <ning.li@intel.com>
Reviewed-on: http://android.intel.com:8080/33511
Reviewed-by: Zhang, Shijie <shijie.zhang@intel.com>
Reviewed-by: Gross, Mark <mark.gross@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>