Revert "hvc_console: display printk messages on console."

This reverts commit 36116245.

It causes an infinite loop when booting Linux under Xen, as so:

  [    2.382984] console [hvc0] enabled
  [    2.382984] console [hvc0] enabled
  [    2.382984] console [hvc0] enabled
  ...

as reported by Konrad Rzeszutek Wilk.  And Rusty reports the same for
lguest.  He goes on to say:

   "This is not a concurrency problem: the issue seems to be that
    calling register_console() twice on the same struct console is a bad
    idea."

and Greg says he'll fix it up properly at some point later. Revert for now.
Reported-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: NRusty Russell <rusty@ozlabs.org>
Requested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Miche Baker-Harvey <miche@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/tty/hvc/hvc_console.c

@@ -852,7 +852,7 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
 	 * find index to use:
 	 * see if this vterm id matches one registered for console.
 	 */
-	for (i = 0; i < MAX_NR_HVC_CONSOLES; i++)
+	for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 		if (vtermnos[i] == hp->vtermno &&
 		    cons_ops[i] == hp->ops)
 			break;
@@ -862,13 +862,9 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
 		i = ++last_hvc;
 
 	hp->index = i;
-	hvc_console.index = i;
-	vtermnos[i] = vtermno;
-	cons_ops[i] = ops;
 
 	list_add_tail(&(hp->next), &hvc_structs);
 	spin_unlock(&hvc_structs_lock);
-	register_console(&hvc_console);
 
 	return hp;
 }
@@ -879,7 +875,6 @@ int hvc_remove(struct hvc_struct *hp)
 	unsigned long flags;
 	struct tty_struct *tty;
 
-	unregister_console(&hvc_console);
 	spin_lock_irqsave(&hp->lock, flags);
 	tty = tty_kref_get(hp->tty);