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/nyan-big_defconfig b/configs/nyan-big_defconfig
index b2a4add..03a752a 100644
--- a/configs/nyan-big_defconfig
+++ b/configs/nyan-big_defconfig
@@ -28,6 +28,7 @@
 CONFIG_CMD_TPM_TEST=y
 CONFIG_CMD_EXT4_WRITE=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