selftests/hid: fix kfunc inclusions with newer bpftool

bpftool now embeds the kfuncs definitions directly in the generated
vmlinux.h

This is great, but because the selftests dir might be compiled w

selftests/hid: fix kfunc inclusions with newer bpftool

bpftool now embeds the kfuncs definitions directly in the generated
vmlinux.h

This is great, but because the selftests dir might be compiled with
HID_BPF disabled, we have no guarantees to be able to compile the
sources with the generated kfuncs.

If we have the kfuncs, because we have the `__not_used` hack, the newly
defined kfuncs do not match the ones from vmlinux.h and things go wrong.

Prevent vmlinux.h to define its kfuncs and also add the missing `__weak`
symbols for our custom kfuncs definitions

Link: https://patch.msgid.link/20241128-fix-new-bpftool-v1-1-c9abdf94a719@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

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Revert "HID: bpf: allow write access to quirks field in struct hid_device"

This reverts commit 6fd47effe92b, and the related self-test update
commit e14e0eaeb040 ("selftests/hid: add test for assign

Revert "HID: bpf: allow write access to quirks field in struct hid_device"

This reverts commit 6fd47effe92b, and the related self-test update
commit e14e0eaeb040 ("selftests/hid: add test for assigning a given
device to hid-generic").

It results in things like the scroll wheel on Logitech mice not working
after a reboot due to the kernel being confused about the state of the
high-resolution mode.

Quoting Benjamin Tissoires:
"The idea of 6fd47effe92b was to be able to call hid_bpf_rdesc_fixup()
once per reprobe of the device.

However, because the bpf filter can now change the quirk value, the
call had to be moved before the driver gets bound (which was
previously ensuring the unicity of the call).

The net effect is that now, in the case hid-generic gets loaded first
and then the specific driver gets loaded once the disk is available,
the value of ->quirks is not reset, but kept to the value that was set
by hid-generic (HID_QUIRK_INPUT_PER_APP).

Once hid-logitech-hidpp kicks in, that quirk is now set, which creates
two inputs for the single mouse: one keyboard for fancy shortcuts, and
one mouse node.

However, hid-logitech-hidpp expects only one input node to be attached
(it stores it into hidpp->input), and when a wheel event is received,
because there is some processing with high-resolution wheel events,
the wheel event is injected into hidpp->input.

And of course, when HID_QUIRK_INPUT_PER_APP is set, hidpp->input gets
the keyboard node, which doesn't have wheel event type, and the events
are ignored"

Reported-and-bisected-by: Mike Galbraith <efault@gmx.de>
Link: https://lore.kernel.org/all/CAHk-=wiUkQM3uheit2cNM0Y0OOY5qqspJgC8LkmOkJ2p2LDxcw@mail.gmail.com/
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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