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/qemu_mipsel_defconfig b/configs/qemu_mipsel_defconfig
index 0841595..281cf66 100644
--- a/configs/qemu_mipsel_defconfig
+++ b/configs/qemu_mipsel_defconfig
@@ -4,6 +4,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="qemu-mipsel # "
+CONFIG_CMD_IDE=y
 # CONFIG_CMD_LOADB is not set
 # CONFIG_CMD_LOADS is not set
 # CONFIG_CMD_SETEXPR is not set