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/rainier_ramboot_defconfig b/configs/rainier_ramboot_defconfig
index c422c5e..21a833a 100644
--- a/configs/rainier_ramboot_defconfig
+++ b/configs/rainier_ramboot_defconfig
@@ -20,5 +20,6 @@
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_FAT=y
 CONFIG_MAC_PARTITION=y
+CONFIG_ISO_PARTITION=y
 CONFIG_SYS_NS16550=y
 CONFIG_OF_LIBFDT=y