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/polaroid_mid2809pxe04_defconfig b/configs/polaroid_mid2809pxe04_defconfig
index d4c1135..3759ef1 100644
--- a/configs/polaroid_mid2809pxe04_defconfig
+++ b/configs/polaroid_mid2809pxe04_defconfig
@@ -21,5 +21,6 @@
 # CONFIG_CMD_FLASH is not set
 # CONFIG_CMD_FPGA is not set
 # CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_ISO_PARTITION is not set
 CONFIG_AXP_DLDO1_VOLT=3300
 CONFIG_USB_MUSB_HOST=y