arch/xtensa: properly set carrier on/off on espnow driver

In esp_espnow_pktradio.c, after ESP-NOW is successfully initialized in espnow_ifup, call netdev_carrier_on(dev).
In espnow_ifdown, call netdev_carrier_off(dev).

Signed-off-by: Filipe Cavalcanti <filipe.cavalcanti@espressif.com>

arch/xtensa/src/common/espressif/esp_espnow_pktradio.c

@@ -42,6 +42,7 @@
 #include <nuttx/net/ip.h>
 #include <nuttx/spinlock.h>
 #include <nuttx/net/radiodev.h>
+#include <nuttx/net/netdev.h>
 #include <nuttx/net/sixlowpan.h>
 #include <nuttx/wireless/pktradio.h>
 #include <nuttx/wdog.h>
@@ -1098,6 +1099,11 @@ static int espnow_ifup(FAR struct net_driver_s *dev)
 
   priv->txblocked = false;
   priv->bifup = true;
+
+  /* Link is ready for 6LoWPAN; set IFF_RUNNING (ifconfig "RUNNING"). */
+
+  netdev_carrier_on(dev);
+
   return OK;
 }
 
@@ -1148,6 +1154,8 @@ static int espnow_ifdown(FAR struct net_driver_s *dev)
 
   priv->bifup = false;
 
+  netdev_carrier_off(dev);
+
   return OK;
 }