MAINTAINERS: remove defunct acpi4asus project info from asus notebooks section

The acpi4asus project appears to be defunct, according to:
https://sourceforge.net/p/acpi4asus/mailman/acpi4asus-user/
the last posts to the list were done in May 2020 and even then
they were mostly spam.

And the http://acpi4asus.sf.net website still talks about 2.6.x kernels.

Drop the defunct mailing-list and update the W: entry to point to
the new up2date https://asus-linux.org/

 site.

Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Luke D. Jones <luke@ljones.dev>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>