dma: edma: Set debug level to debugging messages

The channel allocated/released messages are very spammy and not really
interesting to users. Change them to "debug" level.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>