UBI: fix refill_wl_user_pool()

If no free PEBs are available refill_wl_user_pool() must not
return with -ENOSPC immediately.
It has to block till produce_free_peb() produced a free PEB.
Reported-and-Tested-by: NRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/ubi/wl.c

@@ -599,10 +599,6 @@ static void refill_wl_user_pool(struct ubi_device *ubi)
 	return_unused_pool_pebs(ubi, pool);
 
 	for (pool->size = 0; pool->size < pool->max_size; pool->size++) {
-		if (!ubi->free.rb_node ||
-		   (ubi->free_count - ubi->beb_rsvd_pebs < 1))
-			break;
-
 		pool->pebs[pool->size] = __wl_get_peb(ubi);
 		if (pool->pebs[pool->size] < 0)
 			break;