staging: greybus: lights: avoid NULL deref

staging: greybus: lights: avoid NULL deref

gb_lights_light_config() stores channel_count before allocating the
channels array. If kcalloc() fails, gb_lights_release() iterates the
non-zero count and dereferences light->channels, which is NULL.

Allocate channels first and only then publish channels_count so the
cleanup path can't walk a NULL pointer.

Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
Link: https://lore.kernel.org/all/20260108103700.15384-1-chaitanyamishra.ai@gmail.com/
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Chaitanya Mishra <chaitanyamishra.ai@gmail.com>
Link: https://patch.msgid.link/20260108151254.81553-1-chaitanyamishra.ai@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>