arm: lpc18xx_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: NShawn Lin <shawn.lin@rock-chips.com>
Acked-by: NJoachim Eastwood <manabian@gmail.com>
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

arch/arm/configs/lpc18xx_defconfig

@@ -119,7 +119,6 @@ CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_EHCI_ROOT_HUB_TT=y
 CONFIG_MMC=y
 CONFIG_MMC_DW=y
-CONFIG_MMC_DW_IDMAC=y
 CONFIG_NEW_LEDS=y
 CONFIG_LEDS_CLASS=y
 CONFIG_LEDS_PCA9532=y