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/dbau1550_el_defconfig b/configs/dbau1550_el_defconfig
index dfe0102..7d50000 100644
--- a/configs/dbau1550_el_defconfig
+++ b/configs/dbau1550_el_defconfig
@@ -10,3 +10,4 @@
 # CONFIG_CMD_FPGA is not set
 # CONFIG_CMD_SETEXPR is not set
 # CONFIG_CMD_NFS is not set
+# CONFIG_ISO_PARTITION is not set