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/platinum_picon_defconfig b/configs/platinum_picon_defconfig
index fc0768a..053931e 100644
--- a/configs/platinum_picon_defconfig
+++ b/configs/platinum_picon_defconfig
@@ -48,6 +48,7 @@
 CONFIG_MTDPARTS_DEFAULT="mtdparts=gpmi-nand:14M(spl),2M(uboot),512k(env1),512k(env2),495M(ubi0),14M(res0),2M(res1),512k(res2),512k(res3),-(ubi1)"
 CONFIG_CMD_UBI=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_FSL_USDHC=y
 CONFIG_NAND=y
 CONFIG_NAND_MXS=y