arm64: dts: zynqmp: Use decimal values for drm-clock properties

arm64: dts: zynqmp: Use decimal values for drm-clock properties

The #clock-cells and clock-accuracy properties are all expressed in
decimal, except for the drm-clock. Fix it, as decimal is easier to read
for those properties.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>