diag: Enable masks for user pd memory device session

Currently, masks are not getting enabled on peripherals
when launching user pd memory device session. The patch
takes care to enable the masks properly.

CRs-Fixed: 2051486
Change-Id: I8aa38310f5ec20a41aa0a0e123033d6c8cb38d48
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>