ATI HDMI audio stops functioning after resuming from suspend.

Nothing appears muted. Just stops outputting audio once the machine resumes
from standby. Disabling and reenabling from 'Audio Volume' has no effect on
restoring sound and the settings there all look fine. Function is restored when
the system is restarted so it's definitely related to sleep/suspend. I do not
use hibernate so that's not a factor.

I'm using a Kaveri APU with the integrated video and HDMI (no add-on video).
Issue occurred both before and after installing the AMDGPU-PRO drivers. So it
doesn't seem to be related to that.