stm32/boards/STM32F769DISC: Configure for use with mboot by default.

This is a good board to demonstrate the use of Mboot because it only has a
USB HS port exposed so the native ST DFU mode cannot be used.  With Mboot
this port can be used.

ports/stm32/boards/STM32F769DISC/mpconfigboard.mk

@@ -1,7 +1,18 @@
+# By default this board is configured to use mboot which must be deployed first
+USE_MBOOT ?= 1
+
 MCU_SERIES = f7
 CMSIS_MCU = STM32F769xx
 MICROPY_FLOAT_IMPL = double
 AF_FILE = boards/stm32f767_af.csv
+
+ifeq ($(USE_MBOOT),1)
+# When using Mboot all the text goes together after the filesystem
+LD_FILES = boards/stm32f769.ld boards/common_blifs.ld
+TEXT0_ADDR = 0x08020000
+else
+# When not using Mboot the ISR text goes first, then the rest after the filesystem
 LD_FILES = boards/stm32f769.ld boards/common_ifs.ld
 TEXT0_ADDR = 0x08000000
 TEXT1_ADDR = 0x08020000
+endif