[nrf fromtree] tests: mspi: flash: Add scenario for new mspi_dw option

Add test scenario for a Kconfig option that was recently added to
the mspi_dw driver. Testing it requires performing some transfers
on the MSPI bus with some device, hence flash chip test used.

Signed-off-by: Andrzej Głąbek <[email protected]>
(cherry picked from commit b624a07)

Author: anangl

tests/drivers/mspi/flash/boards/nrf54h20dk_nrf54h20_cpuapp.overlay

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		mspi0 = &exmif;
+	};
+};
+
+&gpio6 {
+	status = "okay";
+};
+
+&exmif {
+	status = "okay";
+};
+
+&mx25uw63 {
+	status = "okay";
+};

tests/drivers/mspi/flash/testcase.yaml

@@ -1,16 +1,18 @@
 # Copyright (c) 2024 Ambiq Micro Inc. <www.ambiq.com>
 # SPDX-License-Identifier: Apache-2.0
 
+common:
+  tags:
+    - drivers
+    - mspi
+    - flash
+  harness: ztest
+
 tests:
   drivers.mspi.flash:
-    tags:
-      - drivers
-      - mspi
-      - flash
     filter: dt_compat_enabled("zephyr,mspi-emul-flash")
       or dt_compat_enabled("jedec,spi-nor") or dt_compat_enabled("jedec,mspi-nor")
       or dt_compat_enabled("mspi-atxp032") or dt_compat_enabled("mspi-is25xX0xx")
-    harness: ztest
     platform_allow:
       - native_sim
       - apollo3p_evb
@@ -20,15 +22,17 @@ tests:
       - apollo3p_evb
       - apollo510_evb
   drivers.mspi.flash.xip_read:
-    tags:
-      - drivers
-      - mspi
-      - flash
     filter: dt_compat_enabled("mspi-is25xX0xx")
-    harness: ztest
     platform_allow:
       - apollo510_evb
     integration_platforms:
       - apollo510_evb
     extra_configs:
       - CONFIG_FLASH_MSPI_XIP_READ=y
+  drivers.mspi.flash.mspi_dw_system_workqueue:
+    filter: dt_alias_exists("mspi0") and dt_compat_enabled("jedec,mspi-nor")
+      and CONFIG_MSPI_DW
+    integration_platforms:
+      - nrf54h20dk/nrf54h20/cpuapp
+    extra_configs:
+      - CONFIG_MSPI_DW_HANDLE_FIFOS_IN_SYSTEM_WORKQUEUE=y