power: supply: ab8500: Call battery population once

The code was calling ab8500_bm_of_probe() in four different
spots effectively overwriting the same configuration three
times. This was done because probe order was uncertain.

Since we now used componentized probe, call it only once
while probing the main charging component.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>