net/mlx4_en: use kzalloc

Use kzalloc instead of kmalloc + memset.

The semantic patch that makes this change is:
(https://coccinelle.gitlabpages.inria.fr/website/)

//<smpl>
@@
expression res, size, flag;
@@
- res = kmalloc(size, flag);
+ res = kzalloc(size, flag);
  ...
- memset(res, 0, size);
//</smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20220312102705.71413-3-Julia.Lawall@inria.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -1067,7 +1067,7 @@ static int mlx4_en_config_rss_qp(struct mlx4_en_priv *priv, int qpn,
 	struct mlx4_qp_context *context;
 	int err = 0;
 
-	context = kmalloc(sizeof(*context), GFP_KERNEL);
+	context = kzalloc(sizeof(*context), GFP_KERNEL);
 	if (!context)
 		return -ENOMEM;
 
@@ -1078,7 +1078,6 @@ static int mlx4_en_config_rss_qp(struct mlx4_en_priv *priv, int qpn,
 	}
 	qp->event = mlx4_en_sqp_event;
 
-	memset(context, 0, sizeof(*context));
 	mlx4_en_fill_qp_context(priv, ring->actual_size, ring->stride, 0, 0,
 				qpn, ring->cqn, -1, context);
 	context->db_rec_addr = cpu_to_be64(ring->wqres.db.dma);