bpf: Cleanup unused function declaration

All usage and the definition of `bpf_prog_free_linfo()` has been removed
in commit e16301fbe1 ("bpf: Simplify freeing logic in linfo and
jited_linfo"). Clean up its declaration in the header file.

Signed-off-by: Ruiqi Gong <gongruiqi@huaweicloud.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/all/20230602030842.279262-1-gongruiqi@huaweicloud.com/
Link: https://lore.kernel.org/bpf/20230606021047.170667-1-gongruiqi@huaweicloud.com

include/linux/filter.h

@@ -874,7 +874,6 @@ void bpf_prog_free(struct bpf_prog *fp);
 
 bool bpf_opcode_in_insntable(u8 code);
 
-void bpf_prog_free_linfo(struct bpf_prog *prog);
 void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
 			       const u32 *insn_to_jit_off);
 int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog);