As ulpi_reset gpio is now optional, we need to check it when doing
the 'dwc3_generic_remove' function. Check if it is declared before
accessing the ulpi_reset.
Fixes: 237d1f60b1d ("usb: dwc3: Use the devm_gpiod_get_optional()
API for reset gpio")
Reported-by: Thomas Nizan <tnizan@witekio.com>
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>