Separate backend operations into control and console operations. Main
idea is that each device has single set of console ops (conmux or
console) and at most one way to control it. Each backend driver exports
a structure with the set of callbacks.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Instad of hand-coding message sending, create a single wrapper that
sends messages to the client.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
