intel_mid_pmic: update pmic driver

intel_mid_pmic: update pmic driver

BZ: 27883

This driver separates the interface for accessing PMIC device register
function into a independent PMIC driver, making it more clear in logic.

Change-Id: Ib19f6d14911f6f7e8dbcd79d1d8dcc44cadc223e
Signed-off-by: Shijie Zhang <shijie.zhang@intel.com>
Reviewed-on: http://android.intel.com:8080/39500
Reviewed-by: Du, Alek <alek.du@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>