Basic Unsorted Block Image (UBI) support v3 (#6)

UBI (Latin: "where?") stands for "Unsorted Block Images". It is a volume management system for flash devices which manages multiple logical volumes on a single physical flash device and spreads the I/O load (i.e, wear-leveling) across the whole flash chip.

In a sense, UBI may be compared to the Logical Volume Manager (LVM). Whereas LVM maps logical sectors to physical sectors, UBI maps logical eraseblocks to physical eraseblocks. But besides the mapping, UBI implements global wear-leveling and I/O errors handling.

For more details, Please visit the following URL.
http://www.linux-mtd.infradead.org/doc/ubi.html

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index 6538f7a..d225a68 100644
@@ -25,6 +25,7 @@ include $(TOPDIR)/config.mk
 
 LIB	:= $(obj)libmtd.a
 
+COBJS-$(CONFIG_CMD_UBI) += mtdcore.o mtdpart.o
 COBJS-$(CONFIG_HAS_DATAFLASH) += at45.o
 COBJS-$(CONFIG_FLASH_CFI_DRIVER) += cfi_flash.o
 COBJS-$(CONFIG_HAS_DATAFLASH) += dataflash.o