msm: Add MSM IOMMU support

Add support for the IOMMUs found on the upcoming Qualcomm
MSM8x60 chips. These IOMMUs allow virtualization of the
address space used by most of the multimedia cores on these
chips.

Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>