qcacld-3.0: Fix deadlock of rmmod and wlan start module

On cnss2 platform, the cnss callbacks in wlan driver are called with
serialization, and in wlan driver stop module and start module has
mutex of iface_change_lock, it might hit deadlock if race condition
happen of rmmod and start module, because start module might call
pld_power_on for this case.

Fix by setting unload flag earlier in __hdd_module_exit which in
different context of cnss serialized work queue, it prevents new
interface open at this point and wait for external thread complete
after it, it close race window before call wlan_hdd_pld_remove.

Change-Id: I8eb3740701070428c59f1fe3e8d2f439d9173413
CRs-Fixed: 2265691

core/hdd/src/wlan_hdd_main.c

@@ -12403,6 +12403,13 @@ static void __hdd_module_exit(void)
 	if (!hdd_wait_for_recovery_completion())
 		return;
 
+	cds_set_driver_loaded(false);
+	cds_set_unload_in_progress(true);
+
+	if (!cds_wait_for_external_threads_completion(__func__))
+		hdd_warn("External threads are still active attempting "
+			 "driver unload anyway");
+
 	if (hdd_ctx)
 		qdf_cancel_delayed_work(&hdd_ctx->iface_idle_work);