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/r2dplus_defconfig b/configs/r2dplus_defconfig
index 3bd3d21..ba68b50 100644
--- a/configs/r2dplus_defconfig
+++ b/configs/r2dplus_defconfig
@@ -1,6 +1,7 @@
 CONFIG_SH=y
 CONFIG_TARGET_R2DPLUS=y
 CONFIG_BOOTDELAY=-1
+CONFIG_CMD_IDE=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_PING=y
 CONFIG_CMD_CACHE=y