dmaengine: mmp_tdma: Log an error if channel is in wrong state

Let's log an error if the channel can't be prepared because it is in an
unexpected state.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Link: https://lore.kernel.org/r/20200419164912.670973-6-lkundrak@v3.sk


Signed-off-by: Vinod Koul <vkoul@kernel.org>