mmc: MMC_MTK should depend on HAS_DMA

If NO_DMA=y:

    ERROR: "dma_alloc_coherent" [drivers/mmc/host/mtk-sd.ko] undefined!
    ERROR: "dma_unmap_sg" [drivers/mmc/host/mtk-sd.ko] undefined!
    ERROR: "dma_map_sg" [drivers/mmc/host/mtk-sd.ko] undefined!
    ERROR: "dma_free_coherent" [drivers/mmc/host/mtk-sd.ko] undefined!

Add a dependency on HAS_DMA to fix this.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/Kconfig

@@ -779,6 +779,7 @@ config MMC_TOSHIBA_PCI
 
 config MMC_MTK
 	tristate "MediaTek SD/MMC Card Interface support"
+	depends on HAS_DMA
 	help
 	  This selects the MediaTek(R) Secure digital and Multimedia card Interface.
 	  If you have a machine with a integrated SD/MMC card reader, say Y or M here.