kconfig: introduce kconfig for UBI

move the UBI config options into Kconfig.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andrew F. Davis <afd@ti.com>
Reviewed by: Evgeni Dobrev <evgeni at studio-punkt.com>
diff --git a/configs/ea20_defconfig b/configs/ea20_defconfig
index 5e31c1b..0e28878 100644
--- a/configs/ea20_defconfig
+++ b/configs/ea20_defconfig
@@ -16,6 +16,7 @@
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y
+CONFIG_CMD_UBI=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SYS_NS16550=y