iommu: add a function to get MID/PID/BID info

For certain use cases SID remains same and when an
smmu page fault occurs it becomes difficult for client
to identify which of the usecases is actually causing
the fault. In such cases MID/PID/BID info can help.
So, add a function for the same so that clients can
call this from their fault handler and get the info.

Change-Id: Ia720641224f908287ae1d66908ab12def82bbbab
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>