Change kern.evdev.rcpt_mask to 12 by default

Change kern.evdev.rcpt_mask from 3 to 12 by default. This makes us much
more evdev-friendly, and will prevent everyone using xorg and wayland with
evdev devices (the default) from needing to change this locally.

powerpc32 still uses the old value for the keyboard part, becaues the adb
keyboard driver used there is not evdev compatible.

Reviewed by: wulf
Approved by: wulf
MFC after: 2 weeks
X-MFC-Note: 12 only
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D24370