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/brppt1_mmc_defconfig b/configs/brppt1_mmc_defconfig
index d0ee619..50e447a 100644
--- a/configs/brppt1_mmc_defconfig
+++ b/configs/brppt1_mmc_defconfig
@@ -66,6 +66,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="am335x-brppt1-mmc"
 CONFIG_OF_SPL_REMOVE_PROPS="pinctrl-0 pinctrl-names clocks clock-names interrupt-parent interrupt-controller interrupt-cells dma-names dmas "
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM=y
 CONFIG_SPL_DM=y