adsprpc: Make hibernation flag channel specific

Make in_hib flag unique to each device. Earlier code uses global flag and
causes memory leaks.With hibernation restore, TZ loses its state. Avoid
hyp assign of secure buffers back to HLOS as ownership by default is
with HLOS.

Change-Id: I20dbd1bec8f1f363a9e64f7c41887446b92154f4
Signed-off-by: Anuj Garg <anujgarg@codeaurora.org>