[nrf fromtree] boards: nordic: nrf54lm20dk: Extend ext memory node with reset GPIO

Extend external memory node with 'reset-gpios' property.

Signed-off-by: Sebastian Głąb <[email protected]>
(cherry picked from commit 4330c06a20a15a4ae76e8c2b36e75a4465226f2a)

Author: nordic-segl

boards/nordic/nrf54lm20dk/nrf54lm20a_cpuapp_common.dtsi

@@ -166,5 +166,6 @@ zephyr_udc0: &usbhs {
 		has-dpd;
 		t-enter-dpd = <10000>;
 		t-exit-dpd = <35000>;
+		reset-gpios = <&gpio2 0 GPIO_ACTIVE_LOW>;
 	};
 };