msm: adsprpc: fix UAF process init_mem

Process init memory allowed to initialize only once
to fix possible improper acecss from remote processor.

Change-Id: Ic1a13738146fcf0d170abd76b50bdc6a75871755
Acked-by: Abhinav Parihar <parihar@qti.qualcomm.com>
Signed-off-by: Vamsi Krishna Gattupalli <quic_vgattupa@quicinc.com>