[nrf fromtree] tests: udc: rework driver test configuration

Distinguish between test case dependencies where a board has a test
feature "usbd" and where no dependency is required other than the
devicetree overlay file, as here to build the UDC skeleton driver.

Signed-off-by: Johann Fischer <[email protected]>
(cherry picked from commit 1695eed)

Author: jfischer-no

tests/drivers/udc/boards/native_sim_native_64.conf

@@ -1,8 +1,15 @@
+common:
+  tags:
+    - usb
+    - drivers
 tests:
   drivers.usb.udc:
-    tags:
-      - usb
-      - drivers
-    platform_allow:
+    depends_on: usbd
+    integration_platforms:
       - nrf52840dk/nrf52840
+  drivers.usb.udc.skeleton:
+    extra_args:
+      - EXTRA_DTC_OVERLAY_FILE="udc_skeleton.overlay"
+      - CONFIG_UDC_BUF_POOL_SIZE=32768
+    platform_allow:
       - native_sim/native/64