msm: ADSPRPC: Initialize hlist node pointers

Initialize the hlist node with valid previous node pointer
that would allow for the node to be deleted in error scenarios
where the buffer being passed from user space is invalid.

Change-Id: Ib16ed9ad2b39ca616563a2e5315951461212de64
Signed-off-by: Sathish Ambley <sathishambley@codeaurora.org>