iommu/omap: Correct init value of iotlb_entry valid field

iommu/omap: Correct init value of iotlb_entry valid field

The iotlb_entry field values are used directly in omap2_alloc_cr,
a function used in preparing the MMU_CAM and MMU_RAM registers.
The iotlb_entry.valid value is being set incorrectly to 1 at the
moment, and this would result in overriding the PAGESIZE bit field
of the MMU_CAM register if prefetching of the entries were to be
supported.

The bug has not caused any MMU faults due to incorrect size
programming so far as the prefetching is disabled by default. Fix
this by using the correct init value for the iotlb_entry.valid
field.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>