HID: i2c-hid: implement ll_driver transport-layer callbacks

Add output_report and raw_request to i2c-hid.
The current implementation of i2c_hid_output_raw_report decides
by itself if it should use a direct send of the output report
or use the data register (SET_REPORT). Split that by reimplement
the logic in __i2c_hid_output_raw_report() which will be dropped
soon.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>