net: ipc_router: Fix use after free of xprt_info pointer

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: I9614774d3c06b028921f54f21406e70ca0943fb4
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>