usb: dwc3: gadget: Introduce a DWC3 VBUS draw callback

Some devices support charging while in device mode.  In these situations,
the USB gadget will notify the DWC3 gadget driver to modify the current
based on the enumeration and device state.  The usb_phy_set_power() API
will allow external charger entities to adjust the charge current through
the notifier block.

Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/1609283011-21997-2-git-send-email-wcheng@codeaurora.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>