ARM: davinci: remove mmc dma resources

The davinci_mmc driver no longer uses platform resources for getting dma
channels. Instead lookup is now done using dma_slave_map.

Signed-off-by: David Lechner <david@lechnology.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>