qcacmn: Add CONFIG_CNSS_OUT_OF_TREE flag

Use CONFIG_CNSS_OUT_OF_TREE to control if CNSS family drivers are
built from in-kernel-tree source or out-of-kernel-tree source since
the exposed header files will be in different paths. This is also
for backward compatibility.

Change-Id: I698492f175ea140e6854c372f366a63f36de24c9
CRs-fixed: 3022556

utils/nlink/src/wlan_nlink_srv.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2020 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2021 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -265,7 +265,11 @@ qdf_export_symbol(nl_srv_is_initialized);
 #include <qdf_mem.h>
 #include <wlan_nlink_common.h>
 #include <net/genetlink.h>
+#ifdef CONFIG_CNSS_OUT_OF_TREE
+#include "cnss_nl.h"
+#else
 #include <net/cnss_nl.h>
+#endif
 
 void cld80211_oem_send_reply(struct sk_buff *msg, void *hdr,
 				    struct nlattr *nest, int flags)