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/sama5d36ek_cmp_nandflash_defconfig b/configs/sama5d36ek_cmp_nandflash_defconfig
index c7f47cc..d48f47e 100644
--- a/configs/sama5d36ek_cmp_nandflash_defconfig
+++ b/configs/sama5d36ek_cmp_nandflash_defconfig
@@ -32,6 +32,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="sama5d36ek_cmp"
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_DM=y
 CONFIG_CLK=y