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/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 50bc5a5..d902558 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -315,7 +315,7 @@
 		return 0;
 	}
 
-	ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
+	ret = request_irq(port->irq, altera_uart_interrupt, 0,
 			DRV_NAME, port);
 	if (ret) {
 		pr_err(DRV_NAME ": unable to attach Altera UART %d "