sh64: Fix irq_intc build failure.

Needs interrupt.h:

  CC      arch/sh64/kernel/irq_intc.o
arch/sh64/kernel/irq_intc.c: In function 'make_intc_irq':
arch/sh64/kernel/irq_intc.c:179: error: implicit declaration of function 'disable_irq_nosync'
make[1]: *** [arch/sh64/kernel/irq_intc.o] Error 1

Signed-off-by: Paul Mundt <lethal@linux-sh.org>