add missing lance_* exports

This patch fixes the following build error:

<--  snip  -->

...
  Building modules, stage 2.
  MODPOST 1203 modules
ERROR: "lance_open" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_close" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_tx_timeout" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_set_multicast" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_start_xmit" [drivers/net/mvme147.ko] undefined!
...
make[2]: *** [__modpost] Error 1

<--  snip  -->
Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/net/7990.c

@@ -506,6 +506,7 @@ int lance_open (struct net_device *dev)
 
 	return res;
 }
+EXPORT_SYMBOL_GPL(lance_open);
 
 int lance_close (struct net_device *dev)
 {
@@ -521,6 +522,7 @@ int lance_close (struct net_device *dev)
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(lance_close);
 
 void lance_tx_timeout(struct net_device *dev)
 {
@@ -529,7 +531,7 @@ void lance_tx_timeout(struct net_device *dev)
 	dev->trans_start = jiffies;
 	netif_wake_queue (dev);
 }
-
+EXPORT_SYMBOL_GPL(lance_tx_timeout);
 
 int lance_start_xmit (struct sk_buff *skb, struct net_device *dev)
 {
@@ -586,6 +588,7 @@ int lance_start_xmit (struct sk_buff *skb, struct net_device *dev)
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(lance_start_xmit);
 
 /* taken from the depca driver via a2065.c */
 static void lance_load_multicast (struct net_device *dev)
@@ -654,6 +657,7 @@ void lance_set_multicast (struct net_device *dev)
 	if (!stopped)
 		netif_start_queue (dev);
 }
+EXPORT_SYMBOL_GPL(lance_set_multicast);
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
 void lance_poll(struct net_device *dev)