diag: Add SMD support

The patch adds SMD support which is required
for diag functionality for peripherals which
still supports SMD.

CRs-Fixed: 2162765
Change-Id: Ieff13b7bb1fb3a91ba65bab2f2382aefb715bbb1
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>
Signed-off-by: Hardik Arya <harya@codeaurora.org>