serial: Kill off NO_IRQ

We transform the offenders into a test of irq <= 0 which will be ok while
the ARM people get their platform sorted. Once that is done (or in a while
if they don't do it anyway) then we will change them all to !irq checks.

For arch specific drivers that are already using NO_IRQ = 0 we just test
against zero so we don't need to re-review them later.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 52fdf60..a1b0a75 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -176,7 +176,7 @@
 		xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
 	}
 	if (xencons_irq < 0)
-		xencons_irq = 0; /* NO_IRQ */
+		xencons_irq = 0;
 	else
 		irq_set_noprobe(xencons_irq);