drivers: net: ethernet: struct sk_buff is declared duplicately

struct sk_buff has been declared. Remove the duplicate.
Signed-off-by: NWan Jiabing <wanjiabing@vivo.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_app.h

@@ -18,7 +18,6 @@ struct netdev_bpf;
 struct netlink_ext_ack;
 struct pci_dev;
 struct sk_buff;
-struct sk_buff;
 struct nfp_app;
 struct nfp_cpp;
 struct nfp_pf;