mmc: MMC_OMAP_HS should depend on HAS_DMA

If NO_DMA=y:

    drivers/built-in.o: In function `omap_hsmmc_pre_dma_transfer':
    omap_hsmmc.c:(.text+0x5a0928): undefined reference to `dma_map_sg'
    drivers/built-in.o: In function `omap_hsmmc_dma_cleanup':
    omap_hsmmc.c:(.text+0x5a0e8e): undefined reference to `dma_unmap_sg'
    drivers/built-in.o: In function `omap_hsmmc_dma_callback':
    omap_hsmmc.c:(.text+0x5a1f58): undefined reference to `dma_unmap_sg'
    drivers/built-in.o: In function `omap_hsmmc_post_req':
    omap_hsmmc.c:(.text+0x5a2082): undefined reference to `dma_unmap_sg'

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>