MIPS: GIC: Fix gic_set_affinity infinite loop

There is an infinite loop in gic_set_affinity. When irq_set_affinity
gets called on gic controller, it blocks forever.

Signed-off-by: Tony Wu <tung7970@gmail.com>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5537/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>