Convert CONFIG_CMD_IDE to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_IDE

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/dbau1100_defconfig b/configs/dbau1100_defconfig
index 3fb0967..98b0d40 100644
--- a/configs/dbau1100_defconfig
+++ b/configs/dbau1100_defconfig
@@ -6,6 +6,7 @@
 # CONFIG_CMD_ELF is not set
 # CONFIG_CMD_RUN is not set
 # CONFIG_CMD_SAVEENV is not set
+CONFIG_CMD_IDE=y
 # CONFIG_CMD_LOADB is not set
 # CONFIG_CMD_LOADS is not set
 # CONFIG_CMD_FLASH is not set