power: supply: bq27xxx_battery: Add the BQ27Z561 Battery monitor

Add the Texas Instruments BQ27Z561 battery monitor.  The register address
map is laid out the same as compared to other devices within the file.
The battery status register has differing bits to determine if the
battery is full, discharging or dead.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>