MIPS: JZ4740: Use generic irq chip

Use the generic irq chip framework to implement the jz4740 INTC and GPIO irq
chips.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2434/
Patchwork: https://patchwork.linux-mips.org/patch/2771/


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