power: supply: ab8500: add missing destroy_workqueue in ab8500_charger_bind

ab8500_charger_bind misses destroy_workqueue in error path,
this patch fixes that.

Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>