SoCs starting with the S3C2443 contain SPI controllers compatible with the
spi-s3c64xx driver and therefore need separate dma channels for rx and tx.

This patch introduces dma channel declarations for these and changes the
dma-s3c2443.c accordingly.

None of the older SoCs use the spi-dma at all. Most boards bitbang their
spi use and the spi-s3c24xx driver also does not use the dma system.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>