irqchip: sun4i: Fix a comment about mask register initialization

The comment was claiming that we were masking all irqs, while the code actually
*un*masks all of them.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sunxi@googlegroups.com
Link: http://lkml.kernel.org/r/1394733834-26839-4-git-send-email-hdegoede@redhat.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>