MIPS: Fixup last users of irq_chip->typename

The typename member of struct irq_chip was kept for migration purposes
and is obsolete since more than 2 years. Fix up the leftovers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
To: LKML <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Patchwork: http://patchwork.linux-mips.org/patch/661/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>