arm64: dts: tegra210-p2180: Allow ldo2 to go down to 1.8 V

Set regulator-min-microvolt property of ldo2 to 1.8 V in
tegra210-p2180.dtsi. ldo2 is used by the sdmmc1 SDHCI controller and its
voltage needs to be adjusted down to 1.8 V to support faster signaling
modes. It appears that the comment about the SDHCI driver requesting
invalid voltages no longer applies.

Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi

@@ -178,16 +178,7 @@
 
 				vddio_sdmmc: ldo2 {
 					regulator-name = "VDDIO_SDMMC";
-					/*
-					 * Technically this supply should have
-					 * a supported range from 1.8 - 3.3 V.
-					 * However, that would cause the SDHCI
-					 * driver to request 2.7 V upon access
-					 * and that in turn will cause traffic
-					 * to be broken. Leave it at 3.3 V for
-					 * now.
-					 */
-					regulator-min-microvolt = <3300000>;
+					regulator-min-microvolt = <1800000>;
 					regulator-max-microvolt = <3300000>;
 					regulator-always-on;
 					regulator-boot-on;