msm: adsprpc: send non-zero message PID for process kill message

Currently, since remote process kill is a kernel RPC call, a zero
pid is sent in its message. Send the actual HLOS pid for the
process kill message so that the remote subsystem can identify
which process to kill without needing to map the arguments.

Change-Id: I14c13194baa231a892ed9e8ee269a8cdb1710211
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Himateja Reddy <hmreddy@codeaurora.org>