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/irda/w83977af_ir.c b/drivers/net/irda/w83977af_ir.c
index bb8857a..e641bb2 100644
--- a/drivers/net/irda/w83977af_ir.c
+++ b/drivers/net/irda/w83977af_ir.c
@@ -215,16 +215,16 @@
 	
 	/* Allocate memory if needed */
 	self->rx_buff.head =
-		dma_alloc_coherent(NULL, self->rx_buff.truesize,
-				   &self->rx_buff_dma, GFP_KERNEL | __GFP_ZERO);
+		dma_zalloc_coherent(NULL, self->rx_buff.truesize,
+				    &self->rx_buff_dma, GFP_KERNEL);
 	if (self->rx_buff.head == NULL) {
 		err = -ENOMEM;
 		goto err_out1;
 	}
 
 	self->tx_buff.head =
-		dma_alloc_coherent(NULL, self->tx_buff.truesize,
-				   &self->tx_buff_dma, GFP_KERNEL | __GFP_ZERO);
+		dma_zalloc_coherent(NULL, self->tx_buff.truesize,
+				    &self->tx_buff_dma, GFP_KERNEL);
 	if (self->tx_buff.head == NULL) {
 		err = -ENOMEM;
 		goto err_out2;