net: sgi: ioc3-eth: fix usage of GFP_* flags

dma_alloc_coherent always zeroes memory, there is no need for
__GFP_ZERO.  Also doing a GFP_ATOMIC allocation just before a GFP_KERNEL
one is clearly bogus.

Fixes: ed870f6a

 ("net: sgi: ioc3-eth: use dma-direct for dma allocations")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>