UBI: remove bogus assertion

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index c7b0afc..0c05f7b 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -390,7 +390,6 @@
 	vfree(buf);
 out_free_vidh:
 	ubi_free_vid_hdr(ubi, vh);
-	ubi_assert(err < 0);
 	return err;
 }