ubifs: Allow ubifsmount volume reference by number

UBI can mount volumes by name or number  The current code forces you
to name the volume by prepending every name with "ubi:".

>From fs/ubifs/super.c
 * There are several ways to specify UBI volumes when mounting UBIFS:
 * o ubiX_Y    - UBI device number X, volume Y;
 * o ubiY      - UBI device number 0, volume Y;
 * o ubiX:NAME - mount UBI device X, volume with name NAME;
 * o ubi:NAME  - mount UBI device 0, volume with name NAME.

Now any name passed in any of the above forms are allowed.

Also update the configs that referenced ubifsmount.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/include/configs/x600.h b/include/configs/x600.h
index 3082aaa..bb495a1 100644
--- a/include/configs/x600.h
+++ b/include/configs/x600.h
@@ -262,7 +262,7 @@
 	"nand_ubifs=run ubifs_mount ubifs_load ubifsargs addip"		\
 		" addcon addmisc addmtd;"				\
 		"bootm ${kernel_addr} - ${dtb_addr}\0"			\
-	"ubifs_mount=ubi part ubi${boot_part};ubifsmount rootfs\0"	\
+	"ubifs_mount=ubi part ubi${boot_part};ubifsmount ubi:rootfs\0"	\
 	"ubifs_load=ubifsload ${kernel_addr} ${kernel_fs};"		\
 		"ubifsload ${dtb_addr} ${dtb_fs};\0"			\
 	"nand_ubifs=run ubifs_mount ubifs_load ubifsargs addip addcon "	\