net/mlx4: fix sparse warnings on TX control flags, endianess

Fix sparse warnings on incompatibility between the endianess of the ctrl_flags
field of struct mlx4_en_priv to the srcrb_flags field of struct
mlx4_wqe_ctrl_seg by changing the former to be __be32 instead of u32.
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

@@ -453,7 +453,7 @@ struct mlx4_en_priv {
 	int base_qpn;
 
 	struct mlx4_en_rss_map rss_map;
-	u32 ctrl_flags;
+	__be32 ctrl_flags;
 	u32 flags;
 #define MLX4_EN_FLAG_PROMISC	0x1
 #define MLX4_EN_FLAG_MC_PROMISC	0x2