usb: isp1760: Move PORT1 configuration to core code

Configuring the mode of operation of port 1 doesn't belong to the HCD
code, as it's related to the soon to come UDC support. Move the
configuration to core code.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>