tests: drivers: spi: loopback: extend nrf overlays with miso/mosi

Add miso-gpios and mosi-gpios to nrf overlays required for
device_deinit testing.

Signed-off-by: Bjarki Arge Andreasen <bjarki.andreasen@nordicsemi.no>

Author: bjarki-andreasen

tests/drivers/spi/spi_loopback/boards/nrf54h20dk_nrf54h20_common.dtsi

@@ -4,6 +4,15 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <zephyr/dt-bindings/gpio/gpio.h>
+
+/ {
+	zephyr,user {
+		miso-gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
+		mosi-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
+	};
+};
+
 &pinctrl {
 	spi130_default: spi130_default {
 		group1 {