ARM: dts: am437x-gp-evm: Add gpio-hog for configuring eMMC/NAND driver

On this board either eMMC or NAND can work based on the level of
spi2_cs0.gpio0_23. Add a gpio-hog to enable configuration of this
pin in the device tree.

Move pinmux for spi2_cs0 (SEL_eMMCorNANDn) out of
NAND node into gpio0 so it is initialized with gpio0.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am437x-gp-evm.dts

@@ -231,7 +231,6 @@ davinci_mdio_sleep: davinci_mdio_sleep {
 
 	nand_flash_x8: nand_flash_x8 {
 		pinctrl-single,pins = <
-			0x26c(PIN_OUTPUT_PULLDOWN | MUX_MODE7)	/* spi2_cs0.gpio/eMMCorNANDsel */
 			0x0  (PIN_INPUT  | MUX_MODE0)	/* gpmc_ad0.gpmc_ad0 */
 			0x4  (PIN_INPUT  | MUX_MODE0)	/* gpmc_ad1.gpmc_ad1 */
 			0x8  (PIN_INPUT  | MUX_MODE0)	/* gpmc_ad2.gpmc_ad2 */
@@ -441,6 +440,12 @@ mcasp1_sleep_pins: mcasp1_sleep_pins {
 			0x144 (PIN_INPUT_PULLDOWN | MUX_MODE7)
 		>;
 	};
+
+	gpio0_pins: gpio0_pins {
+		pinctrl-single,pins = <
+			0x26c (PIN_OUTPUT | MUX_MODE9) /* spi2_cs0.gpio0_23 SEL_eMMCorNANDn */
+		>;
+	};
 };
 
 &i2c0 {
@@ -587,7 +592,23 @@ &ecap0 {
 };
 
 &gpio0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&gpio0_pins>;
 	status = "okay";
+
+	p23 {
+		gpio-hog;
+		gpios = <23 GPIO_ACTIVE_HIGH>;
+		/* SelEMMCorNAND selects between eMMC and NAND:
+		 * Low: NAND
+		 * High: eMMC
+		 * When changing this line make sure the newly
+		 * selected device node is enabled and the previously
+		 * selected device node is disabled.
+		 */
+		output-low;
+		line-name = "SelEMMCorNAND";
+	};
 };
 
 &gpio1 {