Check the service pointer on aidl deinit to avoid
a possible segfault.

Bug: 218900981
Test: adb root
      adb shell
      /vendor/bin/hw/hostapd -i wlan0 -B /data/sigma_dut-ap.conf
      # Should terminate with no output.
Change-Id: I5b814e2bd7539f41136b9de00161eee2301e8d51
diff --git a/hostapd/aidl/aidl.cpp b/hostapd/aidl/aidl.cpp
index 68a7714..e02708c 100644
--- a/hostapd/aidl/aidl.cpp
+++ b/hostapd/aidl/aidl.cpp
@@ -64,8 +64,10 @@
 void hostapd_aidl_deinit(struct hapd_interfaces *interfaces)
 {
 	wpa_printf(MSG_INFO, "Deiniting aidl control");
-	// Before aidl init, make sure call terminate to clear callback_
-	service->terminate();
+	// Before aidl deinit, make sure call terminate to clear callback_
+	if (service) {
+		service->terminate();
+	}
 	eloop_unregister_read_sock(aidl_fd);
 	aidl_fd = -1;
 }