This commit will fix crosvm crashes when playing audio
with ac97 device and null backend
BUG=b:233960497
TEST=run aplay -Dhw:0,0 -d 3 -f dat /dev/urandom inside a VM
Change-Id: Ic24853f308d92b2e5831d112f432f72f6fedd73c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3670934
Commit-Queue: Norman Bintang <normanbt@chromium.org>
Reviewed-by: Chih-Yang Hsia <paulhsia@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
