msm: npu: Allow user code to query if NPUDSP SID is mapped

Add a new interface to allow user code to query if NPUDSP SID is
mapped by IOMMU or not.

Change-Id: I59ae9a683b9135938927a1180d4ec7e721c21543
Signed-off-by: Da Hoon Pyun <dpyun@codeaurora.org>