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/ap121_defconfig b/configs/ap121_defconfig
index 91ebb3b..f3472ae 100644
--- a/configs/ap121_defconfig
+++ b/configs/ap121_defconfig
@@ -21,6 +21,7 @@
 # CONFIG_CMD_FPGA is not set
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_PING=y
+# CONFIG_ISO_PARTITION is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH=y