dm: Move CONFIG_I2C_COMPAT to Kconfig

Make this option available in Kconfig and clean up the board that uses it.
Note there is also an entry in exynos5-common.h but this affects multiple
boards and should be dropped as part of the Samsung I2C migration to
driver model.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/odroid_defconfig b/configs/odroid_defconfig
index a842837..816a3fa 100644
--- a/configs/odroid_defconfig
+++ b/configs/odroid_defconfig
@@ -3,3 +3,5 @@
 CONFIG_TARGET_ODROID=y
 CONFIG_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="exynos4412-odroid"
+CONFIG_DM_I2C=y
+CONFIG_DM_I2C_COMPAT=y