We use len to store the return value from eth_header().  eth_header()
can return -ETH_HLEN (-14).  We want to pass this back instead of
truncating it to 65522 and returning that.

Signed-off-by: Dan Carpenter <redacted>
---
WARNING: Compile tested only.  I don't have this hardware.  Please check
that I am on the right track.

diff --git a/drivers/isdn/i4l/isdn_net.c b/drivers/isdn/i4l/isdn_net.c
index 2339d73..802ab87 100644
--- a/drivers/isdn/i4l/isdn_net.c
+++ b/drivers/isdn/i4l/isdn_net.c

@@ -1901,7 +1901,7 @@ static int isdn_net_header(struct sk_buff *skb, struct net_device *dev,
 {
 	isdn_net_local *lp = netdev_priv(dev);
 	unsigned char *p;
-	ushort len = 0;
+	int len = 0;
 
 	switch (lp->p_encap) {
 		case ISDN_NET_ENCAP_ETHER: