leds: leds-lp3944: properly handle lp3944_configure fail in lp3944_probe

In current implementation, lp3944_probe return 0 even if lp3944_configure fail.
Therefore, led_classdev_unregister will be executed twice
( in error handling of lp3944_configure and lp3944_remove ).
This patch properly handles lp3944_configure fail in lp3944_probe.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>