If dahdi_span_ops.spanconfig is called multiple times in a row (like when
running dahdi_cfg; dahdi_cfg ) the tx signaling bits would go through a spurious
state that some far side devices would respond to.
Now, if the dahdi_span_ops.spanconfig callback is called, and the configuration
matches the existing configuration, we will not touch the framer.
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>