HID: uhid: use generic hidinput_input_event()

HID core provides the same functionality and can convert the input event
to a raw output report. We can thus drop UHID_OUTPUT_EV and rely on the
mandatory UHID_OUTPUT.

User-space wasn't able to do anything with UHID_OUTPUT_EV, anyway. They
don't have access to the report fields.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>