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/kp_imx53_defconfig b/configs/kp_imx53_defconfig
index ea6f8f6..9a4c08c 100644
--- a/configs/kp_imx53_defconfig
+++ b/configs/kp_imx53_defconfig
@@ -29,6 +29,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="imx53-kp"
 CONFIG_ENV_IS_IN_MMC=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_I2C_SET_DEFAULT_BUS_NUM=y
 CONFIG_I2C_DEFAULT_BUS_NUMBER=0x1
 CONFIG_FSL_ESDHC_IMX=y