iommu/omap: remove pm_runtime_irq_safe flag for OMAP IOMMUs

This is not needed for anything, and prevents proper PM transitions for
parent devices which is bad in case of ti-sysc; this effectively kills
PM completely. Thus, remove the flag.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>