spi/atmel: use dmaengine_terminate_all() API

The drivers should use dmaengine_terminate_all() API instead of
accessing the device_control which will be deprecated soon

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>