msm: ipc: Return the error codes without modification

The user-space modules perform decisions regarding retransmission etc.
based on the error codes returned by the IPC Router.

So return the error codes as is without any modification to the
user-space.

Change-Id: Ic7012109c446aaeaba74c3a29cffd16c155e7212
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>