a2dp audio HAL: use correct interface version

Do not use AUDIO_DEVICE_API_VERSION_CURRENT version
but AUDIO_DEVICE_API_VERSION_2_0 to reflect the version
actually implemeted.

Change-Id: I31407af7fc4769be1d259ee739422ce9f598be2e
diff --git a/audio_a2dp_hw/audio_a2dp_hw.c b/audio_a2dp_hw/audio_a2dp_hw.c
index 0645201..cd4cdb4 100644
--- a/audio_a2dp_hw/audio_a2dp_hw.c
+++ b/audio_a2dp_hw/audio_a2dp_hw.c
@@ -1146,7 +1146,7 @@
         return -ENOMEM;
 
     adev->device.common.tag = HARDWARE_DEVICE_TAG;
-    adev->device.common.version = AUDIO_DEVICE_API_VERSION_CURRENT;
+    adev->device.common.version = AUDIO_DEVICE_API_VERSION_2_0;
     adev->device.common.module = (struct hw_module_t *) module;
     adev->device.common.close = adev_close;