After the latest changes to atmel-mci, it could not be used with
DMA on the AVR32 platform. This patch will allow to use DMA again
and it will avoid access to MCI register ATMCI_DMA.

Even if the IP version is lower than v3xx and doesn't have the DMA
configuration register, DMA transfers can be used with a different
controller than the Atmel AHB DMA one. For instance, some AVR chips
use the Synopsys DesignWare AHB DMA controller.
Signed-off-by: NHein Tibosch <hein_tibosch@yahoo.es>
Acked-by: NLudovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>