x86: irq: Move irq_router to a per driver priv

At present irq_router is declared as a static struct irq_router in
arch/x86/cpu/irq.c. Since it's a driver control block, it makes sense
to move it to a per driver priv. Adjust existing APIs to accept an
additional parameter of irq_router's udevice.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>