arm64: tegra: Set reg property for display-hub on Tegra186

Technically the display-hub driver could access registers via the
specified region, though it practice it will do so via the display
controllers' register regions.
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra186.dtsi

@@ -702,6 +702,7 @@ i2c-bus {
 
 		display-hub@15200000 {
 			compatible = "nvidia,tegra186-display", "simple-bus";
+			reg = <0x15200000 0x00040000>;
 			resets = <&bpmp TEGRA186_RESET_NVDISPLAY0_MISC>,
 				 <&bpmp TEGRA186_RESET_NVDISPLAY0_WGRP0>,
 				 <&bpmp TEGRA186_RESET_NVDISPLAY0_WGRP1>,