8139too: Use disable_irq_nosync() in rtl8139_poll_controller()

Use disable_irq_nosync() instead of disable_irq() as this might be
called in atomic context with netpoll.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>