disk: convert CONFIG_ISO_PARTITION to Kconfig

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay73@gmail.com>
diff --git a/configs/cm5200_defconfig b/configs/cm5200_defconfig
index 55a4a34..a3b0013 100644
--- a/configs/cm5200_defconfig
+++ b/configs/cm5200_defconfig
@@ -16,6 +16,7 @@
 CONFIG_CMD_SNTP=y
 CONFIG_CMD_FAT=y
 CONFIG_MAC_PARTITION=y
+CONFIG_ISO_PARTITION=y
 # CONFIG_PCI is not set
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y