ARM: msm: Remove devices-iommu.c

The iommu devices are registered in software, when they should
really be part of the DT. Since we don't currently have DT
bindings in place for the MSM iommu driver just remove this file
for the time being. This is not removing any functionality anyway
because these devices aren't probing today due to missing clocks.

Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>