usb: dwc3-msm: Support external charging detection

External circuitry can perform USB charger detection, obviating
the need for the USB controller to read the D+/D- lines itself.
Notification of detected charger type would happen by way of the
power_supply_set_type() callback. This patch adds handling of
the POWER_SUPPLY_PROP_TYPE property to set the detected charger
type in the dwc3-msm driver and bypass the internal driver-based
detection routine.

Change-Id: Icf32bd418a189de901c5f47034ed0b0a317aef5f
Signed-off-by: Jack Pham <jackp@codeaurora.org>