workqueue: add myself as a dedicated reviwer

I am one of the dedicated reviwers of workqueue.c. Now I add myself
to the MAINTAINERS entry with the updated email address.

The old laijs@cn.fujitsu.com will be ended soon.
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

MAINTAINERS

@@ -11165,6 +11165,7 @@ F:	sound/soc/codecs/wm*
 
 WORKQUEUE
 M:	Tejun Heo <tj@kernel.org>
+R:	Lai Jiangshan <jiangshanlai@gmail.com>
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git
 S:	Maintained
 F:	include/linux/workqueue.h