hal: retry a2dp path start up when failed

Check if a2dp path start failed and do retry from
out_write to recover the path is possible, which
can avoid blocking write if path set up failed.

Bug: 148926518
Change-Id: I479386e1760b214c1be31d34449a068e41ff5ced
diff --git a/hal/audio_extn/a2dp.c b/hal/audio_extn/a2dp.c
index 8422846..4bd9125 100644
--- a/hal/audio_extn/a2dp.c
+++ b/hal/audio_extn/a2dp.c
@@ -2524,6 +2524,7 @@
         if (ret != 0 ) {
            ALOGE("BT controller start failed");
            a2dp.a2dp_source_started = false;
+           ret = -ETIMEDOUT;
         } else {
            if (configure_a2dp_encoder_format() == true) {
                 a2dp.a2dp_source_started = true;