asoc : send chanel mixer while rerouting sound device

Channel mixer has to sent while the sound devices are rerouted
as capture/playback prepare will not be called during rerouting.

Change-Id: I8473d89c7aff9f5f2a1dd2f3f4a8fa5d387b2429
Signed-off-by: Manoj Kumar N D <quic_mnd@quicinc.com>