bluez: Add pre-condition for sound through headphone jack

By default SabreLite board plays sound through HDMI connector.
In case tester want to output sound through headphone connector he should
configure PulseAudio for it.

After the 2 first commands (set-default-sink and set-sink-port) the sound
is heard correctly, but not after a reboot. This is due to mute state not
saved at this time, this needs the third command (after reboot) to fix it.
Further reboot will play sound correctly.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

test-cases/bluez-hfp.yaml

@@ -29,6 +29,13 @@ metadata:
     - "Please note that connman disables bluetooth by default on a fresh image."
     - "Enable device:"
     - "$ connmanctl enable bluetooth"
+    - "When running the test on SabreLite boards using the headphone jack to
+       check the audio output, PulseAudio needs to be configured to route it
+       accordingly as it defaults to the HDMI output:"
+    - $ pacmd set-default-sink alsa_output.platform-sound.stereo-fallback
+    - $ pacmd set-sink-port alsa_output.platform-sound.stereo-fallback analog-output-headphones
+    - "After reboot ensure that headphones will not be muted:"
+    - $ pacmd set-sink-mute alsa_output.platform-sound.stereo-fallback false
 
 
   expected:

test-cases/bluez-phone.yaml

@@ -32,6 +32,14 @@ metadata:
   pre-conditions:
     - "If running the test on an SDK image, kill the blueman-applet process, as
        it prevents the test from installing its own pairing agent."
+    - "When running the test on SabreLite boards using the headphone jack to
+       check the audio output, PulseAudio needs to be configured to route it
+       accordingly as it defaults to the HDMI output:"
+    - $ pacmd set-default-sink alsa_output.platform-sound.stereo-fallback
+    - $ pacmd set-sink-port alsa_output.platform-sound.stereo-fallback analog-output-headphones
+    - "After reboot ensure that headphones will not be muted:"
+    - $ pacmd set-sink-mute alsa_output.platform-sound.stereo-fallback false
+
 
   expected:
     - "If PASSED is displayed, all of the test have passed. The output should be