leds: move LEDS_GPIO_REGISTER out of menuconfig NEW_LEDS

Commit 4440673a ("leds: provide helper to register "leds-gpio"
devices") broke the display of the NEW_LEDS menu as it didn't depend on
NEW_LEDS and so made "LED drivers" and "LED Triggers" appear at the same
level as "LED Support" instead of below it as it was before 4440673a.

Moving LEDS_GPIO_REGISTER out of the menuconfig NEW_LEDS fixes this
unintended side effect.

Reported-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>