iommu/omap: Fix the permissions on nr_tlb_entries

The permissions on the debugfs entry "nr_tlb_entries" should
have been octal, not decimal, so fix it.

Signed-off-by: Suman Anna <s-anna@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>