ARM: davinci: da830-evm: use gpio lookup entries for usb gpios

Add lookup entries for vbus and overcurrent gpios for da830-evm.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>