usb: dwc3: core: add external vBus supply support for ulpi phy

usb: dwc3: core: add external vBus supply support for ulpi phy

Some ULPI USB PHY does not support internal VBUS supply, to drive the CPEN
pin, which requires the configuration of the ULPI DRVVBUSEXTERNAL bit of
OTG_CTRL register.

Added 'snps,ulpi-ext-vbus-drv' a DT property to configure the USB2 PHY to
drive VBUS with an external supply, by setting the USB2 PHY ULPIEXTVBUSDRV
bit[:17] of the GUSB2PHYCFG register to drive VBUS with an external supply.

Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
Link: https://lore.kernel.org/r/20230215093146.5812-3-piyush.mehta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>