drivers:net: dma_alloc_coherent: use __GFP_ZERO instead of memset(, 0)

Reduce the number of calls required to alloc
a zeroed block of memory.

Trivially reduces overall object size.

Other changes around these removals
o Neaten call argument alignment
o Remove an unnecessary OOM message after dma_alloc_coherent failure
o Remove unnecessary gfp_t stack variable

Signed-off-by: Joe Perches <joe@perches.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 e23f023..74464c3 100644
--- a/drivers/net/ethernet/intel/ixgb/ixgb_main.c
+++ b/drivers/net/ethernet/intel/ixgb/ixgb_main.c
@@ -717,12 +717,11 @@
 	txdr->size = ALIGN(txdr->size, 4096);
 
 	txdr->desc = dma_alloc_coherent(&pdev->dev, txdr->size, &txdr->dma,
-					GFP_KERNEL);
+					GFP_KERNEL | __GFP_ZERO);
 	if (!txdr->desc) {
 		vfree(txdr->buffer_info);
 		return -ENOMEM;
 	}
-	memset(txdr->desc, 0, txdr->size);
 
 	txdr->next_to_use = 0;
 	txdr->next_to_clean = 0;