net: Expose a way to know if the network interface is suspended or not

And use it in the shell to display such information then.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

include/net/net_if.h

@@ -2133,7 +2133,6 @@ static inline bool net_if_are_pending_tx_packets(struct net_if *iface)
 }
 
 #ifdef CONFIG_NET_POWER_MANAGEMENT
-
 /**
  * @brief Suspend a network interface from a power management perspective
  *
@@ -2152,6 +2151,14 @@ int net_if_suspend(struct net_if *iface);
  */
 int net_if_resume(struct net_if *iface);
 
+/**
+ * @brief Check if the network interface is suspended or not.
+ *
+ * @param iface Pointer to network interface
+ *
+ * @return True if interface is suspended, False otherwise.
+ */
+bool net_if_is_suspended(struct net_if *iface);
 #endif /* CONFIG_NET_POWER_MANAGEMENT */
 
 /** @cond INTERNAL_HIDDEN */

subsys/net/ip/net_if.c

@@ -3650,6 +3650,11 @@ int net_if_resume(struct net_if *iface)
 	return 0;
 }
 
+bool net_if_is_suspended(struct net_if *iface)
+{
+	return net_if_flag_is_set(iface, NET_IF_SUSPENDED);
+}
+
 #endif /* CONFIG_NET_POWER_MANAGEMENT */
 
 #if defined(CONFIG_NET_PKT_TIMESTAMP_THREAD)

subsys/net/ip/net_shell.c

@@ -306,6 +306,12 @@ static void iface_cb(struct net_if *iface, void *user_data)
 		return;
 	}
 
+#ifdef CONFIG_NET_POWER_MANAGEMENT
+	if (net_if_is_suspended(iface)) {
+		PR_INFO("Interface is suspended, thus not able to tx/rx.\n");
+	}
+#endif
+
 	if (net_if_get_link_addr(iface) &&
 	    net_if_get_link_addr(iface)->addr) {
 		PR("Link addr : %s\n",