TTY: irq: Remove IRQF_DISABLED

Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 6d43f55..b84c834 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -2017,7 +2017,7 @@
 	if (error)
 		goto fail_unregister;
 
-	error = request_irq(IRQ_AMIGA_RBF, ser_rx_int, IRQF_DISABLED,
+	error = request_irq(IRQ_AMIGA_RBF, ser_rx_int, 0,
 			    "serial RX", state);
 	if (error)
 		goto fail_free_irq;