power: supply: ab8500: Fix error handling in ab8500_charger_init()

The ab8500_charger_init() returns the platform_driver_register() directly
without checking its return value, if platform_driver_register() failed,
all ab8500_charger_component_drivers are not unregistered.

Fix by unregister ab8500_charger_component_drivers when
platform_driver_register() failed.

Fixes: 1c1f13a0 ("power: supply: ab8500: Move to componentized binding")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>