arm64: tegra: Drop incorrect maxim,disable-etr on Smaug

There is no "maxim,disable-etr" property (but there is
maxim,enable-etr), neither in the bindings nor in the Linux driver:

  tegra210-smaug.dtb: regulator@1c: Unevaluated properties are not allowed ('maxim,disable-etr' was unexpected)
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra210-smaug.dts

@@ -1395,7 +1395,6 @@ max77621_gpu: regulator@1c {
 			maxim,dvs-default-state = <1>;
 			maxim,enable-active-discharge;
 			maxim,enable-bias-control;
-			maxim,disable-etr;
 			maxim,enable-gpio = <&pmic 6 GPIO_ACTIVE_HIGH>;
 			maxim,externally-enable;
 		};