bpf: devmap: remove redundant assignment of dev = dev

The assignment dev = dev is redundant and should be removed.

Detected by CoverityScan, CID#1469486 ("Evaluation order violation")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

kernel/bpf/devmap.c

@@ -352,7 +352,7 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
-	struct net_device *dev = dev = obj ? obj->dev : NULL;
+	struct net_device *dev = obj ? obj->dev : NULL;
 
 	return dev ? &dev->ifindex : NULL;
 }