smb347_charger: Disable OTG during shutdown(Rebased from R3-main to R3-stable).

smb347_charger: Disable OTG during shutdown(Rebased from R3-main to R3-stable).

BZ: 37067

Adding a .shutdown function, which disables the OTG.
This is required for the case where we shutdown and OTG is removed.
Unless OTG is disabled during shutdown, OTG-Enable bit in Command Register A
is not cleared in the next boot.

Change-Id: I9110659253d6650ced0cf85af3ff9ff1689b3dfe
Signed-off-by: madhu <madhukumarx.kallappa.manjanna@intel.com>
Reviewed-on: http://android.intel.com:8080/51150
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>