udp: Remove unused function declaration udp_bpf_get_proto()

commit 8a59f9d1 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
left behind this.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20230801133902.3660-1-yuehaibing@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/udp.h

@@ -529,7 +529,6 @@ static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
 
 #ifdef CONFIG_BPF_SYSCALL
 struct sk_psock;
-struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
 int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
 #endif