qcacmn: Rename nan_utils_i.h to nan_main_i.h

Rename nan_utils_i.h to nan_main_i.h, because it is supposed to contain
few internal structures along with apis

Change-Id: I77e44c362f2a36c5b17bcaa62cb2f2124abf0245
CRs-Fixed: 2014795

umac/nan/core/src/nan_utils_i.h → umac/nan/core/src/nan_main_i.h

@@ -17,10 +17,11 @@
  */
 
 /**
- * DOC: contains declaration of common utility APIs to be used in NAN modules
+ * DOC: contains declaration of common utility APIs and private structs to be
+ * used in NAN modules
  */
 
-#ifndef _WLAN_NAN_UTILS_H_
-#define _WLAN_NAN_UTILS_H_
+#ifndef _WLAN_NAN_MAIN_I_H_
+#define _WLAN_NAN_MAIN_I_H_
 
 #endif