HID: bpf: add in-tree HID-BPF fix for the Wacom ArtPen

HID: bpf: add in-tree HID-BPF fix for the Wacom ArtPen

This pen is compatible with multiple Wacom tablets, but we only add support
for the Intuos Pro 2 M, as this is the one our user reported the bug
against.

We can not generically add all compatible Wacom tablets as we are
writing the offsets by hand.

The point of this HID-BPF program is to work around a firmware limitation
where the pressure is repeated every other report.
Given that we know this will happen, we can change the first new pressure
information with the mean compared to the previous one. This way we
smooth the incoming pressure without losing information.

Cc: Ping Cheng <pinglinux@gmail.com>
Cc: Jason Gerecke <killertofu@gmail.com>
Cc: Aaron Armstrong Skomra <skomra@gmail.com>
Cc: Joshua Dickens <Joshua@joshua-dickens.com>
Link: https://lore.kernel.org/r/20240410-bpf_sources-v1-6-a8bf16033ef8@kernel.org
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>