workqueue: Make workqueue_init*() return void

The return values of workqueue_init() and workqueue_early_int() are
always 0, and there is no usage of their return value.  So just make
them return void.

Signed-off-by: Yu Chen <chen.yu@easystack.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
2 files changed