HID: magicmouse: Report battery level over USB

When connected over USB, the Apple Magic Mouse 2 and the Apple Magic
Trackpad 2 register multiple interfaces, one of them is used to report
the battery level.

However, unlike when connected over Bluetooth, the battery level is not
reported automatically and it is required to fetch it manually.

Fix the battery report descriptor and add a timer to fetch the battery
level.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>