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/xilinx_zynqmp_ep_defconfig b/configs/xilinx_zynqmp_ep_defconfig
index 5a564a6..26c4a75 100644
--- a/configs/xilinx_zynqmp_ep_defconfig
+++ b/configs/xilinx_zynqmp_ep_defconfig
@@ -37,6 +37,7 @@
 CONFIG_CMD_TIME=y
 CONFIG_CMD_TIMER=y
 CONFIG_CMD_EXT4_WRITE=y
+# CONFIG_SPL_ISO_PARTITION is not set
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_OF_EMBED=y
 CONFIG_NET_RANDOM_ETHADDR=y