msm: adsprpc: restrict user apps from sending kernel RPC messages

Verify that user applications are not using the kernel RPC message
handle to restrict them from directly attaching to guest OS on the
remote subsystem.

Change-Id: Icfa114a12f2bebbe815eb9930027fded51f717fd
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>