bpf: Sync uapi bpf.h to tools directory

There is a difference between kernel uapi bpf.h and tools
uapi bpf.h. There is no functionality difference, but let
us sync properly to make it easy for later bpf.h update.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240325033842.1693553-1-yonghong.song@linux.dev