It should be helpful to export sysfs of "kcryptd" workqueue in some
cases, such as setting specific CPU affinity of the workqueue.

Besides, also tweak the name format a little. The slash inside a
directory name will be translate into exclamation mark, such as
/sys/devices/virtual/workqueue/'kcryptd!253:0'.
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>