Convert CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/warp7_defconfig b/configs/warp7_defconfig
index 40f9e50..d0b4e74 100644
--- a/configs/warp7_defconfig
+++ b/configs/warp7_defconfig
@@ -54,6 +54,7 @@
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MXC=y
 CONFIG_SUPPORT_EMMC_BOOT=y
+CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE=y
 CONFIG_FSL_USDHC=y
 CONFIG_MTD=y
 CONFIG_PINCTRL=y