ubi: fix swapped arguments to call to ubi_alloc_aeb

Static analysis by CoverityScan detected the ec and pnum
arguments are in the wrong order on a call to ubi_alloc_aeb.
Swap the order to fix this.

Fixes: 91f4285fe3 ("UBI: provide helpers to allocate and free aeb elements")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/fastmap.c

@@ -287,7 +287,7 @@ static int update_vol(struct ubi_device *ubi, struct ubi_attach_info *ai,
 
 		/* new_aeb is newer */
 		if (cmp_res & 1) {
-			victim = ubi_alloc_aeb(ai, aeb->ec, aeb->pnum);
+			victim = ubi_alloc_aeb(ai, aeb->pnum, aeb->ec);
 			if (!victim)
 				return -ENOMEM;