soc: qcom: ipc_router_mhi_xprt: Refactor for MHI register

The MHI driver is changing their APIs to use the device
node during registration. This change accommodates the
API changes and callback state changes.

CRs-Fixed: 1095436
Change-Id: I1899d97d676c28b89bb5f85c1a92732f6cfec904
Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>