e100: Use pci pool to work around GFP_ATOMIC order 5 memory allocation failure

pci_alloc_consistent uses GFP_ATOMIC allocation that may fail on some systems
with limited memory (Bug #14265). pci_pool_alloc allows waiting with
GFP_KERNEL.

Tested-by: Karol Lewandowski <karol.k.lewandowski@gmail.com>
Signed-off-by: Roger Oksanen <roger.oksanen@cs.helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>