EM/Battery: Registering for otg callback and getting otg capability

EM/Battery: Registering for otg callback and getting otg capability

BZ: 15398

This patch adds the code for registering the charger driver with
otg driver for callback and obtaining the otg capabilities.
Callback registration and querying otg capabilities functions are
implemented as stubs.

Change-Id: Ia3f9af5f77730c1706a357ba968eeca523c46494
Signed-off-by: Amar Shankar <amarx.shankar@intel.com>
Reviewed-on: http://android.intel.com:8080/43225
Reviewed-by: Pujol, BenjaminX <benjaminx.pujol@intel.com>
Reviewed-by: Tc, Jenny <jenny.tc@intel.com>
Tested-by: P, Eshwar N <eshwar.n.p@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>