UBI: Fastmap: Calc fastmap size correctly

We need to add fm_sb too.

Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Tanya Brokhman <tlinder@codeaurora.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index c701369..cfd5b5e 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -24,7 +24,8 @@
 {
 	size_t size;
 
-	size = sizeof(struct ubi_fm_hdr) + \
+	size = sizeof(struct ubi_fm_sb) + \
+		sizeof(struct ubi_fm_hdr) + \
 		sizeof(struct ubi_fm_scan_pool) + \
 		sizeof(struct ubi_fm_scan_pool) + \
 		(ubi->peb_count * sizeof(struct ubi_fm_ec)) + \