samples: net: wifi: add support for building NXP WiFi

Add support for building NXP WiFi. Since the driver typically requires
binary blobs, enable CONFIG_NXP_WIFI_BUILD_ONLY_MODE for this testcase.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>

samples/net/wifi/sample.yaml

@@ -68,3 +68,9 @@ tests:
       - thingy53/nrf5340/cpuapp
     integration_platforms:
       - thingy53/nrf5340/cpuapp
+  sample.net.wifi.nxp_wifi:
+    extra_args:
+      - CONFIG_NXP_WIFI_BUILD_ONLY_MODE=y
+    platform_allow:
+      - frdm_rw612
+      - rd_rw612_bga