drivers/cc2420: do normal assignment instead of memcpy

drivers/cc2420/cc2420.c

@@ -38,7 +38,7 @@ void cc2420_setup(cc2420_t * dev, const cc2420_params_t *params)
     /* set pointer to the devices netdev functions */
     dev->netdev.netdev.driver = &cc2420_driver;
     /* pull in device configuration parameters */
-    memcpy(&dev->params, params, sizeof(cc2420_params_t));
+    dev->params = *params;
     dev->state = CC2420_STATE_IDLE;
     /* reset device descriptor fields */
     dev->options = 0;