power: bq27xxx: fix register numbers of bq27500

bug: according to data sheet some register numbers are wrong.

tested: no

Fixes: d74534c2 ("power: bq27xxx_battery: Add support for additional bq27xxx family devices")
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>