ARM: S3C64XX: Add a new dma request id for device tree based dma channel lookup

Commit 4972a80e16a2 (ARM: SAMSUNG: Add device tree support for pl330 dma
engine wrappers) introduced a new member 'dt_dmach_prop' in the struct
samsung_dma_info which is used to specify the dma channel number property
as obtained from the device tree. It also introduced a new dma request id
'DMACH_DT_PROP' to indicate that a device tree node property represting
the dma channel is available in 'struct samsung_dma_info'.

Add dma request id 'DMACH_DT_PROP' in s3c64xx dma channel id list in order
to maintain compatibility to the changes in the Samsung dma wrappper
operations.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>