arm64: dts: ti: k3-am642-evm: Add VTT GPIO regulator for DDR

Hold the DDR vtt regulator active for functionality.
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20230414073328.381336-10-nm@ti.comSigned-off-by: Vignesh Raghavendra <vigneshr@ti.com>

arch/arm64/boot/dts/ti/k3-am642-evm.dts

@@ -148,6 +148,20 @@ vddb: regulator-4 {
 		regulator-boot-on;
 	};
 
+	vtt_supply: regulator-5 {
+		compatible = "regulator-fixed";
+		regulator-name = "vtt";
+		pinctrl-names = "default";
+		pinctrl-0 = <&ddr_vtt_pins_default>;
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		gpio = <&main_gpio0 12 GPIO_ACTIVE_HIGH>;
+		vin-supply = <&vsys_3v3>;
+		enable-active-high;
+		regulator-always-on;
+		regulator-boot-on;
+	};
+
 	leds {
 		compatible = "gpio-leds";
 
@@ -338,6 +352,12 @@ AM64X_IOPAD(0x025c, PIN_INPUT, 0) /* (D17) MCAN1_RX */
 			AM64X_IOPAD(0x0258, PIN_OUTPUT, 0) /* (C17) MCAN1_TX */
 		>;
 	};
+
+	ddr_vtt_pins_default: ddr-vtt-pins-default {
+		pinctrl-single,pins = <
+			AM64X_IOPAD(0x0030, PIN_OUTPUT_PULLUP, 7) /* (L18) OSPI0_CSN1.GPIO0_12 */
+		>;
+	};
 };
 
 &main_uart0 {