MIPS: JZ4740: Avoid JZ4740-specific naming

Rename the functions including jz4740 in their names to be more generic
in preparation for supporting further SoCs, and for moving this
interrupt controller code to drivers/irqchip.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Patchwork: https://patchwork.linux-mips.org/patch/10146/


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