UBI: nicify image sequence number handling

Move the image seq. number handling from I/O level to the scanning
lever, where it really belongs to. Move the @image_seq_set variable
to the @struct ubi_scan_info structure, which exists only during
scanning.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index b587140..1ea1421 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -563,16 +563,15 @@
  * This function returns zero if the erase counter header is OK, and %1 if
  * not.
  */
-static int validate_ec_hdr(struct ubi_device *ubi,
+static int validate_ec_hdr(const struct ubi_device *ubi,
 			   const struct ubi_ec_hdr *ec_hdr)
 {
 	long long ec;
-	int vid_hdr_offset, leb_start, image_seq;
+	int vid_hdr_offset, leb_start;
 
 	ec = be64_to_cpu(ec_hdr->ec);
 	vid_hdr_offset = be32_to_cpu(ec_hdr->vid_hdr_offset);
 	leb_start = be32_to_cpu(ec_hdr->data_offset);
-	image_seq = be32_to_cpu(ec_hdr->image_seq);
 
 	if (ec_hdr->version != UBI_VERSION) {
 		ubi_err("node with incompatible UBI version found: "
@@ -598,15 +597,6 @@
 		goto bad;
 	}
 
-	if (!ubi->image_seq_set) {
-		ubi->image_seq = image_seq;
-		ubi->image_seq_set = 1;
-	} else if (ubi->image_seq != image_seq) {
-		ubi_err("bad image sequence number %d, expected %d",
-			image_seq, ubi->image_seq);
-		goto bad;
-	}
-
 	return 0;
 
 bad: