[MIPS] Fix pb1200/irqmap.c and apply some missed patches

[MIPS] Fix pb1200/irqmap.c and apply some missed patches

pb1200/irqmap.c had been broken a while due to non-named initializer
and had missed some recent IRQ related changes.  Apply these commits
to this file.

[MIPS] IRQ cleanups
commit 1603b5aca4f15b34848fb5594d0c7b6333b99144
[MIPS] use generic_handle_irq, handle_level_irq, handle_percpu_irq
commit 1417836e81c0ab8f5a0bfeafa90d3eaa41b2a067
[MIPS] Compile __do_IRQ() when really needed
commit e77c232cfc6e1250b2916a7c69225d6634d05a49

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>