To reduce driver resume time, this patch resumes the codecs in parallel
if there are multiple codecs on the bus.

- The PM workqueue of bus is also used to parallel resuming multiple codecs.
- The work item 'pm_work' is renamed to 'suspend_work' to parallel suspending
  codecs.
- Add a work item 'resume_work' to parallel resuming codecs.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>