MIPS: JZ4740: probe CPU interrupt controller via DT

MIPS: JZ4740: probe CPU interrupt controller via DT

Use the generic irqchip_init function to probe irqchip drivers using DT,
and add the appropriate node to the JZ4740 devicetree in place of the
call to mips_cpu_irq_init.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Patchwork: https://patchwork.linux-mips.org/patch/10166/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>