Make max connected audio a2dp device as one

By default five audio a2dp devices can be connected in AOSP
bt-stack, but we support only a2dp streaming at a time. This
is causing ambiguity when connect 2nd pixel, the media profile
is enabled for both 1st and 2nd pixel, causing ambiguity among
user.

Set the maximum connected audio a2dp device as one, which
resolves the ambiguity and when connect 2nd pixel device.

Signed-off-by: Gowtham Anandha Babu <gowtham.anandha.babu@intel.com>

Author: gowthambabu92

bluetooth/overlay-car/frameworks/base/core/res/res/values/config.xml

@@ -33,4 +33,6 @@
         <item>"8087:0aaa"</item>
     </string-array>
 
+    <!-- Max number of connected audio devices supported by Bluetooth stack -->
+    <integer name="config_bluetooth_max_connected_audio_devices">1</integer>
 </resources>