iommu/fsl: Add the window permission flag as a parameter to iommu_window_enable API.

Each iommu window can have access permissions associated with it. Extended the
window_enable API to incorporate window access permissions.

In case of PAMU each window can have its specific set of permissions.

Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>