ASoC: dapm: Don't create routes when creating kcontrols

Attempting to create the route as part of adding a mux control causes us
to attempt to add the same route twice since we loop over all sources
for the mux after creating the control. Instead do the addition in the
callers.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>