mtd: ubi: Select RBTREE option from MTD_UBI Kconfig entry

Expose the RBTREE feature through Kconfig and select this option from the
MTD_UBI option.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Jagan Teki <jagan@openedev.com>
[Rebased on master]
Signed-off-by: Jagan Teki <jagan@openedev.com>

drivers/mtd/ubi/Kconfig

@@ -3,6 +3,7 @@ menu "UBI support"
 config MTD_UBI
 	bool "Enable UBI - Unsorted block images"
 	select CRC32
+	select RBTREE if ARCH_SUNXI
 	help
 	  UBI is a software layer above MTD layer which admits of LVM-like
 	  logical volumes on top of MTD devices, hides some complexities of

lib/Kconfig

@@ -61,6 +61,9 @@ config SPL_TINY_MEMSET
 	  size-constrained envrionments even this may be too big. Enable this
 	  option to reduce code size slightly at the cost of some speed.
 
+config RBTREE
+	bool
+
 source lib/dhry/Kconfig
 
 source lib/rsa/Kconfig