samples: usb: add integration platforms to flash tests in USB MSC sample

Add integration platforms to mass_flash_fatfs and mass_flash_littlefs
tests as these options are tuned for specific platforms.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
diff --git a/samples/subsys/usb/mass/sample.yaml b/samples/subsys/usb/mass/sample.yaml
index 2f3623f..1e4b9d9 100644
--- a/samples/subsys/usb/mass/sample.yaml
+++ b/samples/subsys/usb/mass/sample.yaml
@@ -32,6 +32,10 @@
       - fatfs
     depends_on: usb_device
     filter: dt_compat_enabled("nordic,qspi-nor")
+    integration_platforms:
+      - nrf52840dk_nrf52840
+      - nrf5340dk_nrf5340_cpuapp
+      - adafruit_feather_nrf52840
     extra_configs:
         - CONFIG_LOG_DEFAULT_LEVEL=3
         - CONFIG_APP_MSC_STORAGE_FLASH_FATFS=y
@@ -62,6 +66,10 @@
     min_ram: 32
     depends_on: usb_device
     filter: dt_compat_enabled("nordic,qspi-nor")
+    integration_platforms:
+      - nrf52840dk_nrf52840
+      - nrf5340dk_nrf5340_cpuapp
+      - adafruit_feather_nrf52840
     extra_configs:
         - CONFIG_LOG_DEFAULT_LEVEL=3
         - CONFIG_APP_MSC_STORAGE_FLASH_LITTLEFS=y