refractor WiFi clock setting

Do not set WiFi clock in PHY initializing function, move it to WiFi
   start/stop function.

components/driver/include/driver/periph_ctrl.h

@@ -49,6 +49,8 @@ typedef enum {
     PERIPH_SDIO_SLAVE_MODULE,
     PERIPH_CAN_MODULE,
     PERIPH_EMAC_MODULE,
+    PERIPH_RNG_MODULE,
+    PERIPH_WIFI_MODULE,
     PERIPH_BT_MODULE,
     PERIPH_WIFI_BT_COMMON_MODULE,
 } periph_module_t;