ARM: s3c64xx: Drop unused DMA fields from struct s3c64xx_spi_csinfo

There is no drivers using those fields so remove them and
the remaining initializations.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>