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/etamin_defconfig b/configs/etamin_defconfig
index 31e711d..a74cad9 100644
--- a/configs/etamin_defconfig
+++ b/configs/etamin_defconfig
@@ -60,6 +60,7 @@
 CONFIG_OF_EMBED=y
 CONFIG_DEFAULT_DEVICE_TREE="am335x-draco"
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_BOOTCOUNT_ENV=y
 CONFIG_BOOTCOUNT_BOOTLIMIT=3