usb: dwc3: Don't switch OTG -> peripheral if extcon is present

usb: dwc3: Don't switch OTG -> peripheral if extcon is present

If the extcon device exists, get the mode from the extcon device. If
the controller is DRD and the driver is unable to determine the mode,
only then default the dr_mode to USB_DR_MODE_PERIPHERAL.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Thinh Nguyen <thinhn@synopsys.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Link: https://lore.kernel.org/r/20220403164907.662860-1-andrew.smirnov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>