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/colibri_t20_defconfig b/configs/colibri_t20_defconfig
index 1b040e9..fe5d33b 100644
--- a/configs/colibri_t20_defconfig
+++ b/configs/colibri_t20_defconfig
@@ -25,6 +25,7 @@
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_UBI=y
 # CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_ISO_PARTITION is not set
 CONFIG_SPL_DM=y
 # CONFIG_BLK is not set
 CONFIG_DFU_MMC=y