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/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 390e9e4..3a9705c 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -40,3 +40,5 @@
 source "drivers/mtd/nand/Kconfig"
 
 source "drivers/mtd/spi/Kconfig"
+
+source "drivers/mtd/ubi/Kconfig"