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/apx4devkit_defconfig b/configs/apx4devkit_defconfig
index 89f58e5..993a4f6 100644
--- a/configs/apx4devkit_defconfig
+++ b/configs/apx4devkit_defconfig
@@ -31,6 +31,7 @@
 CONFIG_MTDPARTS_DEFAULT="mtdparts=gpmi-nand:128k(bootstrap),1024k(boot),768k(env),-(root)"
 CONFIG_CMD_UBI=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_MXS_GPIO=y
 CONFIG_MMC_MXS=y
 CONFIG_NAND=y