Decouple WiFi and BT with coexist to reduce bin size

1. Do not link WiFi code when only BT or BLE is used and WiFi is not
used.

2. Do not link coexist code when CONFIG_SW_COEXIST_ENABLE is disabled.

components/esp32/include/esp_wifi_internal.h

@@ -249,6 +249,15 @@ void *wifi_realloc( void *ptr, size_t size );
   */
 void *wifi_calloc( size_t n, size_t size );
 
+/**
+  * @brief     Update WiFi MAC time
+  *
+  * @param     uint32_t time_delta : time duration since the WiFi/BT common clock is disabled
+  *
+  * @return    Always returns ESP_OK
+  */
+typedef esp_err_t (* wifi_mac_time_update_cb_t)( uint32_t time_delta );
+
 /**
   * @brief     Update WiFi MAC time
   *