samsung-laptop: tweak traces

- don't output error when probing features at load
- print the SABI signature if samsung_sabi_init()
  succeed

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Matthew Garrett <mjg@redhat.com>