configs: stm32mp15: Select correct Ethernet driver for trusted mode

Select the correct Ethernet driver from Synopsis.
Initially, "Synopsys Designware Ethernet MAC" driver was wrongly
selected instead of "Synopsys DWC Ethernet QOS device" driver.

Fixes: commit f90b3f5b ("configs: stm32mp15: Enable Ethernet feature")
Signed-off-by: NPatrice Chotard <patrice.chotard@st.com>

configs/stm32mp15_trusted_defconfig

@@ -73,7 +73,7 @@ CONFIG_SPI_FLASH_WINBOND=y
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set
 CONFIG_SPI_FLASH_MTD=y
 CONFIG_DM_ETH=y
-CONFIG_ETH_DESIGNWARE=y
+CONFIG_DWC_ETH_QOS=y
 CONFIG_PHY=y
 CONFIG_PHY_STM32_USBPHYC=y
 CONFIG_PINCONF=y