ARM: dts: pxa: add dma pxamci nodes to pxa3xx

Add the 3 possible mmc controllers on pxa3xx SoCs to the devicetree
description. Add the dma and clocks to the device-tree description of
pxa27x and pxa3xx at the same time.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>