usb: ohci-da8xx: add vbus and overcurrent gpios

There are two users upstream which register external callbacks for
switching the port power on/off and overcurrent protection. Both
users only use two GPIOs for that. Instead of having that functionality
in the board files, move the logic into the OHCI driver - including
the interrupt handler for overcurrent detection.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>