HID: asus: Add support for T100 keyboard

The keyboard dock used with the Asus Transformer T100 series, uses
the same vendor-defined 0xff31 usage-page as some other Asus
keyboards. But with a small twist, it has a small descriptor bug which
needs to be fixed up for things to work.

This commit adds the USB-ID for this keyboard to the hid-asus driver
and makes asus_report_fixup fix the descriptor issue, fixing
various special function keys on this keyboard not working.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>