HID: multitouch: fix Asus ExpertBook P2 P2451FA trackpoint

[ Upstream commit 4eab1c2fe06c98a4dff258dd64800b6986c101e9 ]

The HID descriptor of this device contains two mouse collections, one
for mouse emulation and the other for the trackpoint.

Both collections get merged and, because the first one defines X and Y,
the movemenent events reported by the trackpoint collection are
ignored.

Set the MT_CLS_WIN_8_FORCE_MULTI_INPUT class for this device to be able
to receive its reports.

This fix is similar to/based on commit 40d5bb87377a ("HID: multitouch:
enable multi-input as a quirk for some devices").

Link: https://gitlab.freedesktop.org/libinput/libinput/-/issues/825


Reported-by: Akito <the@akito.ooo>
Tested-by: Akito <the@akito.ooo>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>