omap iommu: update ducati mmu irq define name

2.6.34-rc6 kernel has the Ducati mmu irq define name changed, which is
resulting in compilation error.

Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>