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/PLU405_defconfig b/configs/PLU405_defconfig
index ffad41f..e30a720 100644
--- a/configs/PLU405_defconfig
+++ b/configs/PLU405_defconfig
@@ -10,6 +10,7 @@
 CONFIG_AUTOBOOT_PROMPT="Press SPACE to abort autoboot in %d seconds\n"
 CONFIG_AUTOBOOT_STOP_STR=" "
 CONFIG_CMD_EEPROM=y
+CONFIG_CMD_IDE=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_USB=y
 # CONFIG_CMD_SETEXPR is not set