HID: tpkbd: work even if the new Lenovo Keyboard driver is not configured

c1dcad2d added a new driver configured by
HID_LENOVO_TPKBD but made the hid_have_special_driver entry non-optional which
lead to a recognized but non-working device if the new driver wasn't
configured (which is the correct default).

Signed-off-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>