[vlan] Expose vlan_find() to network card drivers

Some network cards automatically strip the VLAN header, providing the
VLAN tag via a side channel such as a completion queue entry.  These
cards need to be able to report receive completions directly against
the relevant VLAN device.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/vlan.h

  */
 #define VLAN_PRIORITY_IS_VALID( priority ) ( (priority) <= 7 )
 
+extern struct net_device * vlan_find ( struct net_device *trunk,
+				       unsigned int tag );
 extern int vlan_can_be_trunk ( struct net_device *trunk );
 extern int vlan_create ( struct net_device *trunk, unsigned int tag,
 			 unsigned int priority );

src/net/vlan.c

  * @v tag		VLAN tag
  * @ret netdev		VLAN device, if any
  */
-static struct net_device * vlan_find ( struct net_device *trunk,
-				       uint16_t tag ) {
+struct net_device * vlan_find ( struct net_device *trunk, unsigned int tag ) {
 	struct net_device *netdev;
 	struct vlan_device *vlan;