stm32mp1: activate OF_BOARD_SETUP and FDT_FIXUP_PARTITIONS

Update kernel MTD partition in device tree with U-Boot information.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/configs/stm32mp15_basic_defconfig b/configs/stm32mp15_basic_defconfig
index fcd81c9..cc28611 100644
--- a/configs/stm32mp15_basic_defconfig
+++ b/configs/stm32mp15_basic_defconfig
@@ -114,3 +114,4 @@
 CONFIG_USB_GADGET_VENDOR_NUM=0x0483
 CONFIG_USB_GADGET_PRODUCT_NUM=0x5720
 CONFIG_USB_GADGET_DWC2_OTG=y
+CONFIG_FDT_FIXUP_PARTITIONS=y