Bluetooth: Classic: HF: Fix invalid query current calls list issue

The current calls list should not be queried if the SLC is not
connected. Or the error `-ENOTCONN` will be returned by function
`hf_query_current_calls()`.

Check the connection status of HF before submitting a delay-able
worker. Only the SLC is established, submit the delay-able worker.

Signed-off-by: Lyle Zhu <[email protected]>

Author: lylezhu2012

subsys/bluetooth/host/classic/hfp_hf.c

@@ -1281,7 +1281,9 @@ static void ag_indicator_handle_call_held(struct bt_hfp_hf *hf, uint32_t value)
 {
 	struct bt_hfp_hf_call *call;
 
-	k_work_reschedule(&hf->deferred_work, K_MSEC(HF_ENHANCED_CALL_STATUS_TIMEOUT));
+	if (atomic_test_bit(hf->flags, BT_HFP_HF_FLAG_CONNECTED)) {
+		k_work_reschedule(&hf->deferred_work, K_MSEC(HF_ENHANCED_CALL_STATUS_TIMEOUT));
+	}
 
 	LOG_DBG("call setup %d", value);