arm64: zynqmp: Enable CDC ethernet gadget for zcu100/Ultra96

Ethernet is not present on this board that's why there are two other
options how to wire the board to ethernet. The first is asix_eth usb
host converter which is already enabled by default. The second option is
to use USB CDC/RNDIS ethernet gadget.

This patch is enabling CDC which is working with Linux.
With new bind/unbind command there is no need to call usb_ether_init()
from platform code and use for example these commands:

bind /amba/usb0@ff9d0000/dwc3@fe200000 usb_ether
dhcp
unbind /amba/usb0@ff9d0000/dwc3@fe200000

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

configs/avnet_ultra96_rev1_defconfig

@@ -21,6 +21,7 @@ CONFIG_SPL_ATF=y
 CONFIG_SYS_PROMPT="ZynqMP> "
 CONFIG_CMD_BOOTMENU=y
 CONFIG_CMD_MEMTEST=y
+CONFIG_CMD_BIND=y
 CONFIG_CMD_CLK=y
 CONFIG_CMD_DFU=y
 # CONFIG_CMD_FLASH is not set
@@ -66,6 +67,8 @@ CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_WINBOND=y
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set
+CONFIG_DM_ETH=y
+# CONFIG_NETDEVICES is not set
 CONFIG_DEBUG_UART_ZYNQ=y
 CONFIG_DEBUG_UART_ANNOUNCE=y
 CONFIG_ZYNQ_SERIAL=y
@@ -84,6 +87,8 @@ CONFIG_USB_ULPI=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_DOWNLOAD=y
+CONFIG_USB_ETHER=y
+CONFIG_USB_ETH_CDC=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y
 CONFIG_WDT=y

configs/xilinx_zynqmp_zcu100_revC_defconfig

@@ -21,6 +21,7 @@ CONFIG_SPL_ATF=y
 CONFIG_SYS_PROMPT="ZynqMP> "
 CONFIG_CMD_BOOTMENU=y
 CONFIG_CMD_MEMTEST=y
+CONFIG_CMD_BIND=y
 CONFIG_CMD_CLK=y
 CONFIG_CMD_DFU=y
 # CONFIG_CMD_FLASH is not set
@@ -66,6 +67,8 @@ CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_WINBOND=y
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set
+CONFIG_DM_ETH=y
+# CONFIG_NETDEVICES is not set
 CONFIG_DEBUG_UART_ZYNQ=y
 CONFIG_DEBUG_UART_ANNOUNCE=y
 CONFIG_ZYNQ_SERIAL=y
@@ -84,6 +87,8 @@ CONFIG_USB_ULPI=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_DOWNLOAD=y
+CONFIG_USB_ETHER=y
+CONFIG_USB_ETH_CDC=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y
 CONFIG_WDT=y