power: supply: sbs-battery: Don't needlessly set CAPACITY_MODE

According to the smart battery spec (1), the CAPACITY_MODE bit does not
influence the value read from RelativeStateOfCharge(), so don't bother
changing CAPACITY_MODE when doing such a read.

(1) - Smart Battery Data Specification, Rev 1.1, Dec. 11, 1998

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>