drivers/net/mlx4: Use %pV, pr_<level>, printk_once

Remove near duplication of format string constants by using the newly
introduced vsprintf extention %pV to reduce text by 20k or so.

$ size drivers/net/mlx4/built-in.o*
   text	   data	    bss	    dec	    hex	filename
 161367	   1866	  48784	 212017	  33c31	drivers/net/mlx4/built-in.o
 142621	   1866	  46248	 190735	  2e90f	drivers/net/mlx4/built-in.o.new

Use printk_once as appropriate.
Convert printks to pr_<level>, some bare printks now use pr_cont.
Remove now unused #define PFX.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/mlx4/eq.c b/drivers/net/mlx4/eq.c
index 22d0b3b..6d7b2bf 100644
--- a/drivers/net/mlx4/eq.c
+++ b/drivers/net/mlx4/eq.c
@@ -475,10 +475,10 @@
 		mlx4_dbg(dev, "Dumping EQ context %02x:\n", eq->eqn);
 		for (i = 0; i < sizeof (struct mlx4_eq_context) / 4; ++i) {
 			if (i % 4 == 0)
-				printk("[%02x] ", i * 4);
-			printk(" %08x", be32_to_cpup(mailbox->buf + i * 4));
+				pr_cont("[%02x] ", i * 4);
+			pr_cont(" %08x", be32_to_cpup(mailbox->buf + i * 4));
 			if ((i + 1) % 4 == 0)
-				printk("\n");
+				pr_cont("\n");
 		}
 	}