usb: phy-msm-usb: Fix bug in handling POWER_SUPPLY_PROP_TYPE

When the charger detection is done in the USB driver, don't override
the motg->chg_type while processing the power supply callback for
POWER_SUPPLY_PROP_TYPE case. Otherwise USB internal charger types
such as USB_PROPRIETARY_CHARGER will be marked as DCP chargers.

CRs-Fixed: 758663
Change-Id: I84044d45f0da9b04aee8554d2dcd81699646da7c
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>