Users of the IOMMU API (kvm specifically) assume that iommu_unmap()
returns the order of the unmapped page (on success).

Fix msm_iommu_unmap() accordingly.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Cc: David Brown <davidb@codeaurora.org>
Acked-by: NDavid Brown <davidb@codeaurora.org>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>