msm: Platform initialization for the IOMMU driver

Register a driver for the MSM IOMMU devices and a driver
for the translation context devices. Set up the global
IOMMU registers and initialize the context banks.

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