power: supply: ab8500: Cleanup probe in reverse order

It is logical to cleanup in probe's error path in reverse order to
previous actions.  It also makes easier to add additional goto labels
within this error path.

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