UBI: init_volumes: Ignore volumes with no LEBs

UBI assumes that ubi_attach_info will only contain ubi_ainf_volume
structures for volumes with at least one LEB.
In scanning mode this is true because UBI can nicely create a ubi_ainf_volume
on demand while creating the EBA table.

For fastmap this is not true, the fastmap on-flash structure has a list of
all volumes, the ubi_ainf_volume structures are created from this list.
So it can happen that an empty volume ends up in init_volumes().

We can easely deal with that by looking into ->leb_count too.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/ubi/vtbl.c

@@ -591,7 +591,7 @@ static int init_volumes(struct ubi_device *ubi,
 
 		/* Static volumes only */
 		av = ubi_find_av(ai, i);
-		if (!av) {
+		if (!av || !av->leb_count) {
 			/*
 			 * No eraseblocks belonging to this volume found. We
 			 * don't actually know whether this static volume is