bpf: btf: Remove two unused function declarations

Commit db559117 ("bpf: Consolidate spin_lock, timer management into btf_record")
removed the implementations but leave declarations.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20230808145741.33292-1-yuehaibing@huawei.com


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>