qcacmn: Add warning message on qdf_mem_set() document

Add warning message on qdf_mem_set() document.

Change-Id: I82afa828f6bce295533c63b42515e526f1b01110
CRs-Fixed: 2380158

qdf/linux/src/qdf_mem.c

@@ -1588,6 +1588,9 @@ qdf_export_symbol(qdf_mem_set_io);
  * @num_bytes: Number of bytes to be set
  * @value: Byte set in memory
  *
+ * WARNING: parameter @num_bytes and @value are swapped comparing with
+ * standard C function "memset", please ensure correct usage of this function!
+ *
  * Return: None
  */
 void qdf_mem_set(void *ptr, uint32_t num_bytes, uint32_t value)