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: I99e8e4f94644c5d47b4863f89b308bd5de49c1d7
Acked-by: Krishnaiah Tadakamalla <ktadakam@qti.qualcomm.com>
Signed-off-by: Jeya R <jeyr@codeaurora.org>