Description of problem:
hwcert-backend tool can't support to test integrated HDMI audio in RHEL 6.5.
When run hdmi audio test, hwcert-backend reports "Error: aplay command failed". But in fact, I can hear sound via HDMI audio when play sounds with "Sound Preferences" or run command "aplay /usr/share/sounds/alsa/Front_Right.wav -D plughw:0,3".
And output of "aplay -l":
**** List of PLAYBACK Hardware Devices ****
card 0: MID [HDA Intel MID], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: MID [HDA Intel MID], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 0: ALC662 rev3 Analog [ALC662 rev3 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

Part of hwcert-backend output:
This test plays a sound sample and records it to another file.
Please use the Volume Control application and insure that the 
Capture settings will record the sound.
Continue? (y|n) response: y
starting recording while playing demo sound
Error: aplay command failed

How reproducible:
always

Steps to Reproduce:
1.Install RHEL 6.5 64bit and hwcert.
2.run hdmi audio test with command:"hwcert-backend run --test=audio --udi=pci0000:00/0000:00:03.0/sound/card0"
3.Check the hwcert-backend output.

Actual results:
Failed to test integrated HDMI audio.

Expected results:
Can test this device, and HDMI monitor should play the sounds.

Additional info:
Config:
Processor:Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz
Memory: 8GB
Chipset:Intel C226
hwcert version: 1.6.5.2, release 20140611