irqchip: gic: Make gic_default_routable_irq_domain_ops static

The internal irq domain ops for the GIC are not used directly anywhere
else, so make them static. This gets rid of a sparse warning on the
file.

Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1409062410-25891-8-git-send-email-will.deacon@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>