3c59x: balance page maps and unmaps

debug kernel noticed a screw up in 3c59x.  skbs being mapped as page were being
unmapped as singles.  Easy fix.  Tested by myself

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: NDavid S. Miller <davem@davemloft.net>

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

@@ -2460,7 +2460,7 @@ boomerang_interrupt(int irq, void *dev_id)
 #if DO_ZEROCOPY
 					int i;
 					for (i=0; i<=skb_shinfo(skb)->nr_frags; i++)
-							pci_unmap_single(VORTEX_PCI(vp),
+							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,
 											 PCI_DMA_TODEVICE);