scripts/gen-btf.sh: Reduce log verbosity

scripts/gen-btf.sh: Reduce log verbosity

Remove info messages from gen-btf.sh, as they are unnecessarily
detailed and sometimes inaccurate [1].  Verbose log can be produced by
passing V=1 to make, which will set -x for the shell.

[1] https://lore.kernel.org/bpf/CAADnVQ+biTSDaNtoL=ct9XtBJiXYMUqGYLqu604C3D8N+8YH9A@mail.gmail.com/

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20251231183929.65668-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>