3c59x: Fix bad offset spec in skb_frag_dma_map

Recently aded the use of skb_frag_dma_map to 3c59x, but didn't realize it
automatically included the frag_offset internally, as well as provided an option
to specify an extra offset in the parameter list.  We need to specify an offset
of 0 in the parameter list to avoid skb corruption that results in lost
connections.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Linux Kernel list <linux-kernel@vger.kernel.org>
CC: "David S. Miller" <davem@davemloft.net>
CC: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>

drivers/net/ethernet/3com/3c59x.c

@@ -2186,7 +2186,7 @@ boomerang_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 
 			dma_addr = skb_frag_dma_map(&VORTEX_PCI(vp)->dev, frag,
-						    frag->page_offset,
+						    0,
 						    frag->size,
 						    DMA_TO_DEVICE);
 			if (dma_mapping_error(&VORTEX_PCI(vp)->dev, dma_addr)) {