HID: remove hidinput_input_event handler

All the different transport drivers use now the generic event handling
in hid-input. We can remove the handler definitively now.

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