Squashed revert of the mdp iommu hacks:

commit fc6479bc9930706b0501a31188a0d74f2c2baa45
Author: Sultanxda <sultanxda@gmail.com>
Date:   Wed Jun 11 16:42:36 2014 -0700

    Revert "mdp4_overlay: Fix graphical glitches caused by iommu mapping"

    This reverts commit 93feda4c3cb2b921d1786b042928bc79a3ddf38b.

commit 9a57aa15fb4d0d1baf9141c95ca4d2f6bf66ca83
Author: Sultanxda <sultanxda@gmail.com>
Date:   Wed Jun 11 16:42:17 2014 -0700

    Revert "mdp4_overlay: Make sure ion_map_iommu() is successful for all domains all the time"

    This reverts commit 056cce7cdbf3f0a46ab319e44b8a2c492d93d6ae.

commit 5de71b600ab7c40412b3c94001b99760d7a209eb
Author: Sultanxda <sultanxda@gmail.com>
Date:   Wed Jun 11 16:42:00 2014 -0700

    Revert "gpu: ion: Return an integer for ion_unmap_iommu()"

    This reverts commit 1f1b563d22da897973b17f7847a792d1f713e80a.

commit 78993af52210fdaa57ecab535de5a988d8709955
Author: Sultanxda <sultanxda@gmail.com>
Date:   Wed Jun 11 16:41:44 2014 -0700

    Revert "mdp4_overlay: Conditionally call ion_unmap_iommu()"

    This reverts commit 58f36c0011669ad2c44785314609d0a8f979be99.

commit 7a26901de9a3f9d9dbdc9a18b2e4462bbc428602
Author: Sultanxda <sultanxda@gmail.com>
Date:   Wed Jun 11 16:41:02 2014 -0700

    Revert "gpu: ion: Don't issue kernel WARNING for iommu_map failure"

    This reverts commit 4b63eaf2bbf3ee3265fd7081fbff619fe1232a90.