tests: drivers: wifi: Enable board siwx917_rb4338a

Ensure nobdy break compatibility with SiWx91x chipsets.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>

Author: jerome-pouiller

samples/net/wifi/shell/sample.yaml

@@ -12,6 +12,7 @@ tests:
       - cc3220sf_launchxl
       - disco_l475_iot1
       - reel_board
+      - siwx917_rb4338a
     integration_platforms:
       - cc3220sf_launchxl
   sample.net.wifi.mikroe_wifi_bt_click:
@@ -90,3 +91,8 @@ tests:
       - esp32s3_devkitm/esp32s3/procpu
       - esp8684_devkitm
       - esp32c6_devkitc
+  sample.net.wifi.siwx91x_offloaded:
+    extra_args:
+      - CONFIG_WIFI_SILABS_SIWX91X_NET_STACK_OFFLOAD=y
+    platform_allow:
+      - siwx917_rb4338a