net: Add an accessor to know if waiting for ARP

This single-sources the state of the ARP.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/include/net.h b/include/net.h
index 156bdc1..40e8953 100644
--- a/include/net.h
+++ b/include/net.h
@@ -636,6 +636,7 @@
 void net_set_udp_handler(rxhand_f *);	/* Set UDP RX packet handler */
 rxhand_f *net_get_arp_handler(void);	/* Get ARP RX packet handler */
 void net_set_arp_handler(rxhand_f *);	/* Set ARP RX packet handler */
+bool arp_is_waiting(void);		/* Waiting for ARP reply? */
 void net_set_icmp_handler(rxhand_icmp_f *f); /* Set ICMP RX handler */
 void net_set_timeout_handler(ulong, thand_f *);/* Set timeout handler */