libbpf: Remove unused args in parse_usdt_note

Remove unused 'elf' and 'path' parameters from parse_usdt_note function
signature. These parameters are not referenced within the function body
and only add unnecessary complexity.

The function only requires the note header, data buffer, offsets, and
output structure to perform USDT note parsing.

Update function declaration, definition, and the single call site in
collect_usdt_targets() to match the simplified signature.

This is a safe internal cleanup as parse_usdt_note is a static function.

Signed-off-by: Jiawei Zhao <phoenix500526@163.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20250904030525.1932293-1-phoenix500526@163.com