UBI: improve internal interfaces

Pass volume description object to the EBA function which makes
more sense, and EBA function do not have to find the volume
description object by volume ID.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 7697eda..24344ba 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -249,7 +249,7 @@
 		if (off + len >= vol->usable_leb_size)
 			len = vol->usable_leb_size - off;
 
-		err = ubi_eba_read_leb(ubi, vol_id, lnum, tbuf, off, len, 0);
+		err = ubi_eba_read_leb(ubi, vol, lnum, tbuf, off, len, 0);
 		if (err)
 			break;
 
@@ -339,7 +339,7 @@
 			break;
 		}
 
-		err = ubi_eba_write_leb(ubi, vol_id, lnum, tbuf, off, len,
+		err = ubi_eba_write_leb(ubi, vol, lnum, tbuf, off, len,
 					UBI_UNKNOWN);
 		if (err)
 			break;
@@ -484,7 +484,7 @@
 		}
 
 		dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
-		err = ubi_eba_unmap_leb(ubi, vol->vol_id, lnum);
+		err = ubi_eba_unmap_leb(ubi, vol, lnum);
 		if (err)
 			break;