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/r7780mp_defconfig b/configs/r7780mp_defconfig
index 999470c..2a37db8 100644
--- a/configs/r7780mp_defconfig
+++ b/configs/r7780mp_defconfig
@@ -10,6 +10,7 @@
 # CONFIG_CMD_XIMG is not set
 # CONFIG_CMD_EDITENV is not set
 # CONFIG_CMD_ENV_EXISTS 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