The use of handle_percpu_irq() is not really what we want for MSI, use
handle_simple_irq() instead.  This is probably the prototypical case
for using handle_simple_irq(), because all the MSIs are dispatched from
the root interrupt service routine.

Also since the base IRQ is not shared, don't pass IRQF_SHARED.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1488/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>