HID: make .raw_request mandatory

SET_REPORT and GET_REPORT are mandatory in the HID specification.
Make the corresponding API in hid-core mandatory too, which removes the
need to test against it in some various places.

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