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/gluebi.c b/drivers/mtd/ubi/gluebi.c
index 41ff74c..d397219 100644
--- a/drivers/mtd/ubi/gluebi.c
+++ b/drivers/mtd/ubi/gluebi.c
@@ -129,8 +129,7 @@
 		if (to_read > total_read)
 			to_read = total_read;
 
-		err = ubi_eba_read_leb(ubi, vol->vol_id, lnum, buf, offs,
-				       to_read, 0);
+		err = ubi_eba_read_leb(ubi, vol, lnum, buf, offs, to_read, 0);
 		if (err)
 			break;
 
@@ -187,8 +186,8 @@
 		if (to_write > total_written)
 			to_write = total_written;
 
-		err = ubi_eba_write_leb(ubi, vol->vol_id, lnum, buf, offs,
-					to_write, UBI_UNKNOWN);
+		err = ubi_eba_write_leb(ubi, vol, lnum, buf, offs, to_write,
+					UBI_UNKNOWN);
 		if (err)
 			break;
 
@@ -237,7 +236,7 @@
 		return -EROFS;
 
 	for (i = 0; i < count; i++) {
-		err = ubi_eba_unmap_leb(ubi, vol->vol_id, lnum + i);
+		err = ubi_eba_unmap_leb(ubi, vol, lnum + i);
 		if (err)
 			goto out_err;
 	}