drivers/leds/leds-sunfire.c: fix sunfire_led_generic_probe() error handling

- return -ENOMEM if kzalloc fails, rather than the current -EINVAL

- fix a memory leak in the case of goto out_unregister_led_cdevs

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>