MIPS: MSP71xx: Add vectored interrupt support.

This patch will add vectored interrupt setups required for MIPS MT modes.
irq_cic has been restructured and moved per irq handler to different file.
irq_cic has been re wrote to support mips MT modes ( VSMP / SMTC )

[Ralf: fixed some more checkpatch warnings.]

Signed-off-by: Anoop P A <anoop.pa@gmail.com>
To: linux-mips@linux-mips.org
To: linux-kernel@vger.kernel.org
To: dhowells@redhat.com
Patchwork: https://patchwork.linux-mips.org/patch/2041/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>