macvlan: macvlan_count_rx shouldn't be static inline AND extern

It doesn't make sense to define macvlan_count_rx as a static inline and
then add a forward declaration after that as an extern. I am dropping the
extern declaration since it seems like it is something that likely got
missed when the function was made an inline.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

include/linux/if_macvlan.h

@@ -61,10 +61,6 @@ extern int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
 				  struct nlattr *tb[], struct nlattr *data[],
 				  struct netlink_ext_ack *extack);
 
-extern void macvlan_count_rx(const struct macvlan_dev *vlan,
-			     unsigned int len, bool success,
-			     bool multicast);
-
 extern void macvlan_dellink(struct net_device *dev, struct list_head *head);
 
 extern int macvlan_link_register(struct rtnl_link_ops *ops);