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/mscc_jr2_defconfig b/configs/mscc_jr2_defconfig
index f6e7785..4256a75 100644
--- a/configs/mscc_jr2_defconfig
+++ b/configs/mscc_jr2_defconfig
@@ -40,6 +40,7 @@
 CONFIG_DTB_RESELECT=y
 CONFIG_MULTI_DTB_FIT=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_CLK=y
 CONFIG_DM_GPIO=y