msm: ipc: Add support to handle version 2 header

IPC Router Message header is 32 bytes in size since each element uses
4 bytes in size regardless of the data range being represented.

Add a version 2 header format that compacts the header into 16 bytes.

Change-Id: I5e6cfc0672ca1dc3365b31c26d2ce4b3c6230cfc
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>