xsk: Remove dangling function declaration from header file

xdp_umem_query() is dead for a long time, drop the declaration from
include/linux/netdevice.h

Fixes: c9b47cc1 ("xsk: fix bug when trying to use both copy and zero-copy on one queue id")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/20210303185636.18070-2-maciej.fijalkowski@intel.com

include/linux/netdevice.h

@@ -3959,8 +3959,6 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
 u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode);
 
-int xdp_umem_query(struct net_device *dev, u16 queue_id);
-
 int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
 int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
 int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb);