drivers/at86rf2xx: do normal assignment instead of memcpy

drivers/at86rf2xx/at86rf2xx.c

@@ -43,7 +43,7 @@ void at86rf2xx_setup(at86rf2xx_t *dev, const at86rf2xx_params_t *params)
 
     netdev->driver = &at86rf2xx_driver;
     /* initialize device descriptor */
-    memcpy(&dev->params, params, sizeof(at86rf2xx_params_t));
+    dev->params = *params;
     /* State to return after receiving or transmitting */
     dev->idle_state = AT86RF2XX_STATE_TRX_OFF;
     /* radio state is P_ON when first powered-on */