ux500: Add DMA support for U5500

Add basic DMA configuration for u5500 supporting memcpy.
Make way for SDI0 dma support by setting SDI0 to -1,
indicating it will be configured in runtime.

Signed-off-by: Per Forlin <per.forlin@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>