power_supply: charger-manager: Fix dereferencing of ERR_PTR

If power_supply_register() fails do not dereference returned ERR_PTR.
The pointer was dereferenced to print name of battery which registration
failed. Instead use the name from the power supply description passed to
the power_supply_register() function.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>