irqchip: mips-gic: Remove __gic_irq_dispatch() forward declaration

We provide a forward declaration of the __gic_irq_dispatch() function
for no apparent reason. Remove it.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17042/


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