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/ds109_defconfig b/configs/ds109_defconfig
index eea8906..b5ecc12 100644
--- a/configs/ds109_defconfig
+++ b/configs/ds109_defconfig
@@ -12,6 +12,7 @@
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_PING=y
 CONFIG_DOS_PARTITION=y
+CONFIG_ISO_PARTITION=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_STMICRO=y