MFC r308240:

[evdev] Add evdev support to atkbd(4) driver

To enable event sourcing from atkbd kern.evdev.rcpt_mask value
should have bit 3 set.

Submitted by: Vladimir Kondratiev <wulf@cicgroup.ru>
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D8381