defconfigs: Migrate CONFIG_SYS_REDUNDAND_ENVIRONMENT

Move this symbol to Kconfig.  As part of this we can drop a UBI-specific
symbol that was a stop-gap for not having this particular symbol in
Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/brxre1_defconfig b/configs/brxre1_defconfig
index d9b0e32..e1fb102 100644
--- a/configs/brxre1_defconfig
+++ b/configs/brxre1_defconfig
@@ -65,6 +65,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="am335x-brxre1"
 CONFIG_OF_SPL_REMOVE_PROPS=""
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_NETCONSOLE=y
 CONFIG_DM=y