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: Ia4eb34e98224a67740981279f3b81aa0ec2d8be1
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>