BTAudio HAL: Added feature flag for DSA Over LEA

Test: atest VtsHalBluetoothAudioTargetTest
Bug: 270987427
Change-Id: Ifef0b97d20c7c12001b7d04cc7f8ce9da5fb1920
diff --git a/bluetooth/audio/flags/btaudiohal.aconfig b/bluetooth/audio/flags/btaudiohal.aconfig
new file mode 100644
index 0000000..763777e
--- /dev/null
+++ b/bluetooth/audio/flags/btaudiohal.aconfig
@@ -0,0 +1,8 @@
+package: "com.android.btaudio.hal.flags"
+
+flag {
+    name: "dsa_lea"
+    namespace: "pixel_bluetooth"
+    description: "Flag for DSA Over LEA"
+    bug: "270987427"
+}