ARM: ux500: Setup the DMA40 driver's DT node using the new DMA API

The new DMA is now available, so let's use it to setup ST-Ericsson's
DMA40 driver when Device Tree is enabled.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>