power: supply: cw2015: use dev_err_probe to allow deferred probe

Deal with deferred probe using dev_err_probe so the error is handled
and avoid logging lots probe defer information like the following:

[    9.125121] cw2015 4-0062: Failed to register power supply
[    9.211131] cw2015 4-0062: Failed to register power supply

Fixes: b4c7715c ("power: supply: add CellWise cw2015 fuel gauge driver")
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>