MIPS: loongson: lemote-2f: irq: Make internal data static

Make internal static to eliminate the following sparse warnings:
warning: symbol 'ip6_irqaction' was not declared. Should it be static?
warning: symbol 'cascade_irqaction' was not declared. Should it be static?

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8527/


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