HID: Export hid_register_report

The Apple Magic Mouse (and probably other devices) publish reports that are not
called out in their HID report descriptors -- they only send them when enabled
through other writes to the device.  This allows a driver to handle these
unlisted reports.

Signed-off-by: Michael Poole <mdpoole@troilus.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>