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>

drivers/net/wireless/b43legacy/dma.c

@@ -331,10 +331,9 @@ void free_descriptor_buffer(struct b43legacy_dmaring *ring,
 static int alloc_ringmemory(struct b43legacy_dmaring *ring)
 {
 	/* GFP flags must match the flags in free_ringmemory()! */
-	ring->descbase = dma_alloc_coherent(ring->dev->dev->dma_dev,
-					    B43legacy_DMA_RINGMEMSIZE,
-					    &(ring->dmabase),
-					    GFP_KERNEL | __GFP_ZERO);
+	ring->descbase = dma_zalloc_coherent(ring->dev->dev->dma_dev,
+					     B43legacy_DMA_RINGMEMSIZE,
+					     &(ring->dmabase), GFP_KERNEL);
 	if (!ring->descbase)
 		return -ENOMEM;