drivers:net: Convert dma_alloc_coherent(...__GFP_ZERO) to dma_zalloc_coherent

__GFP_ZERO is an uncommon flag and perhaps is better
not used.  static inline dma_zalloc_coherent exists
so convert the uses of dma_alloc_coherent with __GFP_ZERO
to the more common kernel style with zalloc.

Remove memset from the static inline dma_zalloc_coherent
and add just one use of __GFP_ZERO instead.

Trivially reduces the size of the existing uses of
dma_zalloc_coherent.

Realign arguments as appropriate.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/intel/ixgb/ixgb_main.c b/drivers/net/ethernet/intel/ixgb/ixgb_main.c
index fce3e92..9f6b236 100644
--- a/drivers/net/ethernet/intel/ixgb/ixgb_main.c
+++ b/drivers/net/ethernet/intel/ixgb/ixgb_main.c
@@ -718,8 +718,8 @@
 	txdr->size = txdr->count * sizeof(struct ixgb_tx_desc);
 	txdr->size = ALIGN(txdr->size, 4096);
 
-	txdr->desc = dma_alloc_coherent(&pdev->dev, txdr->size, &txdr->dma,
-					GFP_KERNEL | __GFP_ZERO);
+	txdr->desc = dma_zalloc_coherent(&pdev->dev, txdr->size, &txdr->dma,
+					 GFP_KERNEL);
 	if (!txdr->desc) {
 		vfree(txdr->buffer_info);
 		return -ENOMEM;