arm: exynos_defconfig: remove CONFIG_MMC_DW_IDMAC

DesignWare MMC Controller's transfer mode should be decided
at runtime instead of compile-time. So we remove this config
option and read dw_mmc's register to select DMA master.
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

arch/arm/configs/exynos_defconfig

@@ -166,7 +166,6 @@ CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_S3C=y
 CONFIG_MMC_SDHCI_S3C_DMA=y
 CONFIG_MMC_DW=y
-CONFIG_MMC_DW_IDMAC=y
 CONFIG_MMC_DW_EXYNOS=y
 CONFIG_RTC_CLASS=y
 CONFIG_RTC_DRV_MAX77686=y