ubi: wl: Fix uninitialized variable

There is a potential execution path in which variable *err*
is compared against UBI_IO_BITFLIPS without being properly
initialized previously.

Fix this by initializing variable *err* to 0.

Addresses-Coverity-ID: 1477298 "(Uninitialized scalar variable")
Fixes: 663586c0 ("ubi: Expose the bitrot interface")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/wl.c

@@ -1475,7 +1475,7 @@ static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e)
  */
 int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force)
 {
-	int err;
+	int err = 0;
 	struct ubi_wl_entry *e;
 
 	if (pnum < 0 || pnum >= ubi->peb_count) {