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/trimslice_defconfig b/configs/trimslice_defconfig
index f7f7fd3..4b0691e 100644
--- a/configs/trimslice_defconfig
+++ b/configs/trimslice_defconfig
@@ -21,6 +21,7 @@
 # CONFIG_CMD_NFS is not set
 CONFIG_CMD_EXT4_WRITE=y
 # CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_ISO_PARTITION is not set
 CONFIG_SPL_DM=y
 # CONFIG_BLK is not set
 # CONFIG_DM_MMC_OPS is not set