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/scan.h b/drivers/mtd/ubi/scan.h
index 61df208..1017cf1 100644
--- a/drivers/mtd/ubi/scan.h
+++ b/drivers/mtd/ubi/scan.h
@@ -102,6 +102,7 @@
  * @mean_ec: mean erase counter value
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
+ * @image_seq_set: indicates @ubi->image_seq is known
  *
  * This data structure contains the result of scanning and may be used by other
  * UBI sub-systems to build final UBI data structures, further error-recovery
@@ -124,6 +125,7 @@
 	int mean_ec;
 	uint64_t ec_sum;
 	int ec_count;
+	int image_seq_set;
 };
 
 struct ubi_device;