drivers/leds/leds-netxbig.c: use gpio_request_one()

Use gpio_request_one() instead of multiple gpiolib calls.  This also
simplifies error handling a bit.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Simon Guinot <sguinot@lacie.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>