msm: adsprpc: block untrusted apps from creating multiple sessions

Do not allow untrusted apps to create multiple remote sessions.

Change-Id: Ie5e143099b3e546c7423c9dae1256a9e3fc4d76c
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Himateja Reddy <hmreddy@codeaurora.org>