msm: adsprpc: protect the global remote heap buffer list

Protect global remote heap buffer list using spin locks. Validate
buffer before cache flush. Invoke remote process release only when
the context and subsystem status are valid and log the process
release error only if process init was successful. Fail I/O
requests during static PD restart. Log all hyp assign failures.

Change-Id: I20f12ba00ed33c2534faf107d7ca1cbb3695f50a
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>