[ARM] S3C64XX: DMA support

Add support for the DMA blocks in the S3C64XX series of CPUS,
which are based on the ARM PL080 PrimeCell system.

Unfortunately, these DMA controllers diverge from the PL080
design by adding another DMA controller register and
configuration for OneNAND.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>