m68knommu: fix broken setting of irq_chip and handler

Fix compile error, by using correct loop variable:

arch/m68knommu/platform/68328/ints.c: In function ‘init_IRQ’:
arch/m68knommu/platform/68328/ints.c:182: error: ‘irq’ undeclared (first use in this function)
arch/m68knommu/platform/68328/ints.c:182: error: (Each undeclared identifier is reported only once
arch/m68knommu/platform/68328/ints.c:182: error: for each function it appears in.)

Signed-off-by: Greg Ungerer <gerg@uclinux.org>