Quirk based support of Chromebook keyboard found in Acer C720

This probably supports other devices based on SeaBIOS, which need
to be added to the smbios based quirks table.

The functionality has been ported from DragonFlyBSD and adapted
to FreeBSD's more general purpose environment.

Devices not covered by a quirk shouldn't be affected at all. Thanks
to jhb and kostikbel for reviewing the code.

Reviewed by: kostikbel, jhb
Approved by: jhb, kostikbel
Differential Revision: https://reviews.freebsd.org/D1802