xtensa: Fixup irq conversion fallout and nmi_count

Some unnamed moron fatfingered the arguments of the irq chip callbacks
to irq_chip instead of irq_data.

While at it remove the nmi_count() print in arch_show_interrupts()
which has been broken before the irq conversion already.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>