usb: chipidea: udc: add pullup fuction, needed by the uvc gadget

Add function to physicaly enable or disable of pullup connection on the USB-D+
line. The uvc gaget will fail, if this function is not implemented.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>