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/Cubietruck_defconfig b/configs/Cubietruck_defconfig
index 069845c..dc46e2f 100644
--- a/configs/Cubietruck_defconfig
+++ b/configs/Cubietruck_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CMD_USB_MASS_STORAGE=y
 # CONFIG_CMD_FPGA is not set
 # CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_ISO_PARTITION is not set
 CONFIG_DFU_RAM=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_USB_EHCI_HCD=y