usb: chipidea: udc: apply new usb_udc_vbus_handler interface

It can move all pullup/pulldown operation control to udc-core
through usb_gadget_connect/usb_gadget_disconnect according to
vbus status.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>