net: dsa: Export symbols for dsa_port_vid_{add, del}

This is needed so that the newly introduced tag_8021q may access these
core DSA functions when built as a module.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/port.c

@@ -389,6 +389,7 @@ int dsa_port_vid_add(struct dsa_port *dp, u16 vid, u16 flags)
 	trans.ph_prepare = false;
 	return dsa_port_vlan_add(dp, &vlan, &trans);
 }
+EXPORT_SYMBOL(dsa_port_vid_add);
 
 int dsa_port_vid_del(struct dsa_port *dp, u16 vid)
 {
@@ -400,6 +401,7 @@ int dsa_port_vid_del(struct dsa_port *dp, u16 vid)
 
 	return dsa_port_vlan_del(dp, &vlan);
 }
+EXPORT_SYMBOL(dsa_port_vid_del);
 
 static struct phy_device *dsa_port_get_phy_device(struct dsa_port *dp)
 {