arm64: dts: ti: k3-am62-lp-sk-nand: Rename pinctrls to fix schema warnings

Rename pinctrl nodes to comply with naming conventions required by
pinctrl-single schema.

Fixes: e569152 ("arm64: dts: ti: am62-lp-sk: Add overlay for NAND expansion card")
Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Link: https://patch.msgid.link/20251127122733.2523367-3-w.egorov@phytec.de
Signed-off-by: Nishanth Menon <nm@ti.com>

Author: wdmegrv

arch/arm64/boot/dts/ti/k3-am62-lp-sk-nand.dtso

@@ -14,7 +14,7 @@
 };
 
 &main_pmx0 {
-	gpmc0_pins_default: gpmc0-pins-default {
+	gpmc0_pins_default: gpmc0-default-pins {
 		pinctrl-single,pins = <
 			AM62X_IOPAD(0x003c, PIN_INPUT, 0) /* (K19) GPMC0_AD0 */
 			AM62X_IOPAD(0x0040, PIN_INPUT, 0) /* (L19) GPMC0_AD1 */