MIPS: Octeon: Add twsi interrupt initialization for OCTEON 3XXX, 5XXX, 63XX

In octeon_3xxx.dts file, there is a definiton for twsi/twsi2 interrupts.
But there is no code for initialization of this interrupts. This patch adds
code for initialization of twsi interrupts.

Signed-off-by: Eunbong Song <eunb.song@samsung.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6816/


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