ARM: dts: zynq: Enable USB and USB PHY for ZYBO

Setup the USB controller and configure it to operate in host mode.
Additionally add the USB phy node for the ZYBO, including reset gpio
which is connected to a external MIO pin.

Signed-off-by: Nathan Rossi <nathan@nathanrossi.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>