evdev: Sync event codes with Linux kernel 6.5

MFC after: 1 week

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

[evdev] Sync event codes with Linux kernel 5.6

MFC after: 2 weeks

[evdev] Sync event codes with Linux kernel 4.16

MFC after: 2 weeks

Change my email address to wulf@FreeBSD.org in copyright headers.

Approved by: gonzo (mentor)
MFC after: 2 weeks

Add evdev protocol implementation

evdev is a generic input event interface compatible with Linux
evdev API at ioctl level. It allows using unmodified (apart from
header name) input evdev drivers in Xorg, Wayland, Qt.

This commit has only generic kernel API. evdev support for individual
hardware drivers like ukbd, ums, atkbd, etc. will be committed later.

Project was started by Jakub Klama as part of GSoC 2014. Jakub's
evdev implementation was later used as a base, updated and finished
by Vladimir Kondratiev.

Submitted by: Vladimir Kondratiev <wulf@cicgroup.ru>
Reviewed by: adrian, hans
Differential Revision: https://reviews.freebsd.org/D6998