msm: ipc: IPC Router updates to support QMI in the kernel

1) Move the kernel interface APIs to a separate header file.
2) Use platform device to indicate the arrival/exit of service.
3) Add kernel APIs to send and receive messages through IPC Router.
4) Clean up unused Macros, enums, header inclusion.

Change-Id: I1541e9815d104f7ea46d19c10b57c77d967bd065
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>