wlan_platform: Bring initial files for CNSS family drivers

Bring CNSS family drivers from msm-5.10 kernel as of commit
cc3bc4b888af (cnss2: Fix a few switch statement fallthrough
issues) to WLAN platform project. Fix SPDX-License format for
a few files as well.

drivers/net/wireless/cnss* -> .
include/net/cnss* -> inc/

Above shows how directories and header files are relocated.

Change-Id: If8fd40a35c9fdbeb1aa76a8aac5fdb1fc1c7e786

inc/cnss_prealloc.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2015-2016,2019 The Linux Foundation. All rights reserved. */
+
+#ifndef _NET_CNSS_PREALLOC_H_
+#define _NET_CNSS_PREALLOC_H_
+
+#include <linux/types.h>
+
+#define WCNSS_PRE_ALLOC_GET_THRESHOLD (4*1024)
+
+extern void *wcnss_prealloc_get(size_t size);
+extern int wcnss_prealloc_put(void *ptr);
+extern int wcnss_pre_alloc_reset(void);
+void wcnss_prealloc_check_memory_leak(void);
+
+#endif /* _NET_CNSS__PREALLOC_H_ */