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_mips64el_defconfig b/configs/qemu_mips64el_defconfig
index b2d2a0b..5f6ea3e 100644
--- a/configs/qemu_mips64el_defconfig
+++ b/configs/qemu_mips64el_defconfig
@@ -5,6 +5,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="qemu-mips64el # "
+CONFIG_CMD_IDE=y
 # CONFIG_CMD_LOADB is not set
 # CONFIG_CMD_LOADS is not set
 # CONFIG_CMD_SETEXPR is not set