Add OWNERS for audio-related HAL default implementations

Test: not needed
Change-Id: Idefe7be10bde22866be82f87118b9b54e74c3f40
diff --git a/broadcastradio/1.0/default/OWNERS b/broadcastradio/1.0/default/OWNERS
new file mode 100644
index 0000000..b159083
--- /dev/null
+++ b/broadcastradio/1.0/default/OWNERS
@@ -0,0 +1,4 @@
+elaurent@google.com
+krocard@google.com
+mnaganov@google.com
+twasilczyk@google.com