usb: phy-msm-usb: 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 phy-msm-usb driver and bypass the internal driver-based
detection routine.

CRs-Fixed: 718067
Change-Id: If0b37e8c1070dcaffd44399c34bf01ccb7c52983
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>