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/maltael_defconfig b/configs/maltael_defconfig
index a8df759..a4a4a2b 100644
--- a/configs/maltael_defconfig
+++ b/configs/maltael_defconfig
@@ -13,6 +13,7 @@
 CONFIG_CMD_DHCP=y
 # CONFIG_CMD_NFS is not set
 CONFIG_CMD_PING=y
+# CONFIG_ISO_PARTITION is not set
 CONFIG_OF_EMBED=y
 CONFIG_PCI=y
 CONFIG_SYS_NS16550=y