selftests/hid: cleanup C tests by adding a common struct uhid_device
Allows to have an abstract class uhid_device which handles all of the
uhid part without having to mess up with individual fds.
struct attach_prog_args is now never used in hid_bpf.c, so drop it as well
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://patch.msgid.link/20241001-hid-bpf-hid-generic-v3-6-2ef1019468df@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>