iommu: msm: Enable PMU for 8084

Enable Performance Monitor Unit (PMU) on 8084. The PMU
allows you to monitor the performance of the IOMMU which
is useful for debugging perfomance issues.

Change-Id: I0e03d8ce91bbd0d9a27d794b5cd8ae2f6275bb17
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>