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/brsmarc1_defconfig b/configs/brsmarc1_defconfig
index b6626e1..1598a21 100644
--- a/configs/brsmarc1_defconfig
+++ b/configs/brsmarc1_defconfig
@@ -71,6 +71,7 @@
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="am335x-brsmarc1"
 CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_NETCONSOLE=y
 CONFIG_DM=y