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/sandbox_spl_defconfig b/configs/sandbox_spl_defconfig
index cbe4185..761cfb6 100644
--- a/configs/sandbox_spl_defconfig
+++ b/configs/sandbox_spl_defconfig
@@ -38,6 +38,7 @@
 CONFIG_CMD_MX_CYCLIC=y
 CONFIG_CMD_MEMINFO=y
 CONFIG_CMD_DEMO=y
+CONFIG_CMD_IDE=y
 CONFIG_CMD_GPT=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_SPI=y