HID: HIDp: remove hidp_hidinput_event

hidp uses its own ->hidinput_input_event() instead of the generic binding
in hid-input.
Moving the handling of LEDs towards hidp_hidinput_event() allows two things:
- remove hidinput_input_event definitively from struct hid_device
- hidraw user space programs can also set the LEDs

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>