m68knommu: use setup_irq() in ColdFire simple timer

Use setup_irq() instead of request_irq() to set up system timer
in ColdFire simple timer code. With the old m68knommu irq code this
was safe, but it is not now within the generic irq framework.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>