Convert CONFIG_SYS_FAULT_ECHO_LINK_DOWN to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FAULT_ECHO_LINK_DOWN

Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/xilinx_versal_virt_defconfig b/configs/xilinx_versal_virt_defconfig
index 6e7d0ac..8c853ca 100644
--- a/configs/xilinx_versal_virt_defconfig
+++ b/configs/xilinx_versal_virt_defconfig
@@ -55,6 +55,7 @@
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_NETCONSOLE=y
 CONFIG_IP_DEFRAG=y
+CONFIG_SYS_FAULT_ECHO_LINK_DOWN=y
 CONFIG_TFTP_BLOCKSIZE=4096
 CONFIG_CLK_VERSAL=y
 CONFIG_DFU_TIMEOUT=y