ARM: S3C24XX: Add missing DMACH_DT_PROP

Commit 2b908075 (spi: s3c64xx: add device tree support) requires
the DMACH_DT_PROP element in the dma_ch enum. It's not used on non-DT
platforms but has to be present nevertheless.

So mimic the dummy-add of DMACH_DT_PROP on s3c64xx for s3c24xx
machines, to correct the build breakage for the s3c24xx variants
using the s3c64xx-spi-driver.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s3c24xx/include/mach/dma.h

@@ -24,7 +24,8 @@
 */
 
 enum dma_ch {
-	DMACH_XD0,
+	DMACH_DT_PROP = -1,	/* not yet supported, do not use */
+	DMACH_XD0 = 0,
 	DMACH_XD1,
 	DMACH_SDI,
 	DMACH_SPI0,