asus-laptop: fix warning in asus_handle_init

In function 'asus_laptop_get_info':
warning: passing argument 3 of 'asus_handle_init' from incompatible pointer type
note: expected 'char **' but argument is of type 'const char **'

Introduced by commit c21085108a02e1b838c34f3650c8cc9fbd178615
("asus-laptop: fix style problems reported by checkpath.pl").

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Matthew Garrett <mjg@redhat.com>