msm: adsprpc: Handle UAF in process shell memory

Added flag to indicate memory used
in process initialization. And, this memory
would not removed in internal unmap to avoid
UAF or double free.

Change-Id: Ie470fe58ac334421d186feb41fa67bd24bb5efea
Acked-by: Deepika Singh <dsi@qti.qualcomm.com>
Signed-off-by: Jeya R <jeyr@codeaurora.org>