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/malta64el_defconfig b/configs/malta64el_defconfig
index 9b04e0b..ac56046 100644
--- a/configs/malta64el_defconfig
+++ b/configs/malta64el_defconfig
@@ -7,6 +7,7 @@
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="maltael # "
 # CONFIG_AUTOBOOT is not set
+CONFIG_CMD_IDE=y
 # CONFIG_CMD_LOADB is not set
 # CONFIG_CMD_LOADS is not set
 # CONFIG_CMD_FPGA is not set