dt-bindings: phy: zynqmp-psgtr: Fix example's numbers of cells in reg

dt-bindings: phy: zynqmp-psgtr: Fix example's numbers of cells in reg

The DT examples are by default compiled in a parent that has
 #address-cells and #size-cells both set to 1. Fix the example
accordingly, even if it doesn't match the actual hardware, as this is
the recommended practice for DT bindings examples.

Fixes: cea0f76a483d ("dt-bindings: phy: Add DT bindings for Xilinx ZynqMP PSGTR PHY")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20200701134853.30656-1-laurent.pinchart@ideasonboard.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>