leds: Kconfig cleanup

Remove the need for "depends on LEDS_CLASS" by wrapping the affected
config options in an if/endif block. Similar for "depends on LEDS_TRIGGERS".

LEDS_COBALT_RAQ still has a "depends on LEDS_CLASS=y" since it cannot
be selected to build as a module.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>