bpf: Remove unused declaration bpf_link_new_file()

Commit a3b80e107894 ("bpf: Allocate ID for bpf_link")
removed the implementation but not the declaration.

Signed-off-by: Yue Haibing <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin KaFai Lau <[e-mail]>

include/linux/bpf.h

···
 void bpf_link_inc(struct bpf_link *link);
 void bpf_link_put(struct bpf_link *link);
 int bpf_link_new_fd(struct bpf_link *link);
-struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd);
 struct bpf_link *bpf_link_get_from_fd(u32 ufd);
 struct bpf_link *bpf_link_get_curr_or_next(u32 *id);