selftests/hid: fix compilation when bpf_wq and hid_device are not exported

selftests/hid: fix compilation when bpf_wq and hid_device are not exported

This can happen in situations when CONFIG_HID_SUPPORT is set to no, or
some complex situations where struct bpf_wq is not exported.

So do the usual dance of hiding them before including vmlinux.h, and
then redefining them and make use of CO-RE to have the correct offsets.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603111558.KLCIxsZB-lkp@intel.com/
Fixes: fe8d561db3e8 ("selftests/hid: add wq test for hid_bpf_input_report()")
Cc: stable@vger.kernel.org
Acked-by: Jiri Kosina <jkosina@suse.com>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>