NET: hamradio: Fix IP over bpq encapsulation.

Since 1d5da757 (ax25: Stop using magic
neighbour cache operations.) any attempt to transmit IP packets over
a bpqether device will result in a message like "Dead loop on virtual
device bpq0, fix it urgently!"

Fix suggested by Eric W. Biederman <ebiederm@xmission.com>.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@vger.kernel.org> # 4.1
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hamradio/bpqether.c

@@ -482,6 +482,7 @@ static void bpq_setup(struct net_device *dev)
 	memcpy(dev->dev_addr,  &ax25_defaddr, AX25_ADDR_LEN);
 
 	dev->flags      = 0;
+	dev->features	= NETIF_F_LLTX;	/* Allow recursion */
 
 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
 	dev->header_ops      = &ax25_header_ops;