iommu: Fix flags passed to iommu map functions.

iommu map functions requires clients to specify whether
the mappings should be read only or read-write (write only
is not supported). Ensure clients specify the appropriate
flags when calling map functions.

Change-Id: If42b4b0367b4311aa36d3063979ef04af3a43fc6
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>