tests: drivers: build_all: ethernet: test dwmac driver for STM32H7

Add a test case to build the Synopsys DesignWare MAC driver for STM32H7
series SoCs. This drivers is an alternative to the existing ETH_STM32_HAL
driver. As such both drivers cannot be enabled at the same time.

Signed-off-by: Tim Pambor <tim.pambor@codewrights.de>

Author: tpambor

tests/drivers/build_all/ethernet/testcase.yaml

@@ -23,3 +23,12 @@ tests:
       - CONFIG_ETH_STM32_MULTICAST_FILTER=y
     platform_allow:
       - stm32h573i_dk
+
+  net.ethernet.build.stm32_dwmac:
+    extra_configs:
+      - CONFIG_ETH_STM32_HAL=n
+      - CONFIG_MDIO_ST_STM32_HAL=n
+      - CONFIG_ETH_DWMAC_STM32H7X=y
+      - CONFIG_ETH_PHY_DRIVER=n
+    platform_allow:
+      - stm32h735g_disco