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/work_92105_defconfig b/configs/work_92105_defconfig
index a5d76e8..1196b78 100644
--- a/configs/work_92105_defconfig
+++ b/configs/work_92105_defconfig
@@ -36,6 +36,7 @@
 CONFIG_CMD_DATE=y
 CONFIG_DOS_PARTITION=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 # CONFIG_MMC is not set
 CONFIG_PHYLIB=y
 CONFIG_PHY_ADDR_ENABLE=y