net: dsa: tag_8021q: remove struct packet_type declaration

This is no longer necessary since tag_8021q doesn't register itself as a
full-blown tagger anymore.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/dsa/8021q.h

@@ -11,7 +11,6 @@
 struct dsa_switch;
 struct sk_buff;
 struct net_device;
-struct packet_type;
 struct dsa_8021q_context;
 
 struct dsa_8021q_crosschip_link {