HID: ll_driver: Extend the interface with idle requests
Some drivers send the idle command directly to underlying device,
creating an unwanted dependency on the underlying transport layer.
This patch adds hid_hw_idle() to the interface, thereby removing
usbhid from the lion share of the drivers.
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>