net: ipc_router: Fix xprt_info use after free issue

In SSR case the xprt_info pointer is freed without considering the users of
the pointer in TX path will leads to use after free of the pointer.

Use the reference count to keep track of the xprt_info structure and wait
for the all user to complete the task before free the xprt_info pointer.

CRs-Fixed: 999123
Change-Id: I894a877346ff1d395c6f1b06267dfec333cb1024
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>