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/qemu_mipsel_defconfig b/configs/qemu_mipsel_defconfig
index b9226a8..bb1679b 100644
--- a/configs/qemu_mipsel_defconfig
+++ b/configs/qemu_mipsel_defconfig
@@ -10,4 +10,5 @@
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
+# CONFIG_ISO_PARTITION is not set
 CONFIG_SYS_NS16550=y