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/edb9315a_defconfig b/configs/edb9315a_defconfig
index f8f2e16..3c506fd 100644
--- a/configs/edb9315a_defconfig
+++ b/configs/edb9315a_defconfig
@@ -24,6 +24,7 @@
 CONFIG_CMD_JFFS2=y
 # CONFIG_DOS_PARTITION is not set
 CONFIG_ENV_IS_IN_FLASH=y
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_LED_STATUS=y
 CONFIG_LED_STATUS0=y
 CONFIG_LED_STATUS_BIT=0