HID: sony: Set initial battery level to 100% to avoid false low battery warnings

Set the initial battery level to 100% to avoid false low battery warnings if
the battery state is polled before a report with the actual battery level is
received.

Signed-off-by: Frank Praznik <frank.praznik@oh.rr.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>