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/M5329AFEE_defconfig b/configs/M5329AFEE_defconfig
index a689665..4e5fed9 100644
--- a/configs/M5329AFEE_defconfig
+++ b/configs/M5329AFEE_defconfig
@@ -22,6 +22,7 @@
 CONFIG_CMD_DATE=y
 CONFIG_ENV_ADDR=0x4000
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_SYS_FAULT_ECHO_LINK_DOWN=y
 CONFIG_UDP_CHECKSUM=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_FSL=y