3c59x: fix another page map/single unmap imbalance

libdma debug found another page map/unmap imbalance in 3c59x.  Multi fragment
frames are mapped such that the lead fragment was mapped as a single entry,
while all other fragments were mapped as pages.  However, on unmapping they were
all unmapped as pages.  Fix is pretty easy, just unmap the lead frag as a single
entry, and bump the for loop initalization up by one so that all subsequent
frags get unmapped as pages

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Steffen Klassert <klassert@mathematik.tu-chemnitz.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -2459,7 +2459,12 @@ boomerang_interrupt(int irq, void *dev_id)
 					struct sk_buff *skb = vp->tx_skbuff[entry];
 #if DO_ZEROCOPY
 					int i;
-					for (i=0; i<=skb_shinfo(skb)->nr_frags; i++)
+					pci_unmap_single(VORTEX_PCI(vp),
+							le32_to_cpu(vp->tx_ring[entry].frag[0].addr),
+							le32_to_cpu(vp->tx_ring[entry].frag[0].length),
+							PCI_DMA_TODEVICE);
+
+					for (i=1; i<=skb_shinfo(skb)->nr_frags; i++)
 							pci_unmap_page(VORTEX_PCI(vp),
 											 le32_to_cpu(vp->tx_ring[entry].frag[i].addr),
 											 le32_to_cpu(vp->tx_ring[entry].frag[i].length)&0xFFF,