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/am57xx_evm_defconfig b/configs/am57xx_evm_defconfig
index 8a867f6..588e589 100644
--- a/configs/am57xx_evm_defconfig
+++ b/configs/am57xx_evm_defconfig
@@ -40,6 +40,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="am572x-idk"
 CONFIG_OF_LIST="am57xx-beagle-x15 am57xx-beagle-x15-revb1 am57xx-beagle-x15-revc am572x-idk am571x-idk am574x-idk"
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_DM=y
 CONFIG_SPL_DM=y