arm64: dts: imx8mm-phycore: drop uncorrect vselect-en

There is no "vselect-en" property, neither in the bindings nor in the
Linux driver:

  imx8mm-phyboard-polis-rdk.dtb: pmic@8: regulators:ldo2: Unevaluated properties are not allowed ('vselect-en' was unexpected)
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Yannic Moog <y.moog@phytec.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-phycore-som.dtsi

@@ -151,7 +151,6 @@ reg_nvcc_sd2: ldo2 {
 				regulator-max-microvolt = <3300000>;
 				regulator-min-microvolt = <1800000>;
 				regulator-name = "NVCC_SD2 (LDO2)";
-				vselect-en;
 
 				regulator-state-mem {
 					regulator-off-in-suspend;