power: bq27x00_battery: Add manufacturer property

Add the manufacturer property to the bq27x00 driver.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Acked-by: Dan Murphy <dmurphy@ti.com>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>