driver core: platform: remove misleading err_alloc label

In platform_device_register_full() the err_alloc label is
misleading, we only ever jump to it if the pdev is NULL,
but it then proceeds to free it, which is a no-op.

Remove the label and simply exit the function immediately.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>