usb: ehci-omap: select NOP_USB_XCEIV PHY driver

ehci-omap needs NOP_USB_XCEIV PHY driver to function
properly, so select it. As the USB PHY drivers no longer
depend on USB_PHY, it is safe to select the PHY drivers.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Tested-by: Adrien Vergé <adrienverge@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>