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/ib62x0_defconfig b/configs/ib62x0_defconfig
index 2655124..40be266 100644
--- a/configs/ib62x0_defconfig
+++ b/configs/ib62x0_defconfig
@@ -41,6 +41,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NETCONSOLE=y
+CONFIG_SYS_FAULT_ECHO_LINK_DOWN=y
 CONFIG_DM=y
 CONFIG_SYS_ATA_STRIDE=4
 CONFIG_SYS_ATA_DATA_OFFSET=0x100