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/stm32mp15_optee_defconfig b/configs/stm32mp15_optee_defconfig
index 4f4102c..73a1c02 100644
--- a/configs/stm32mp15_optee_defconfig
+++ b/configs/stm32mp15_optee_defconfig
@@ -41,6 +41,7 @@
 CONFIG_ENV_IS_IN_EXT4=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_ENV_IS_IN_UBI=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_ENV_EXT4_INTERFACE="mmc"
 CONFIG_ENV_EXT4_DEVICE_AND_PART="0:auto"
 CONFIG_ENV_EXT4_FILE="/uboot.env"