Necessary modifications in Nuttx for Olimex-STM32-E407 to allow external drivers.

[jfm92]

Now it's not necessary to do this modifications. The modification are already pushed

In this guide I'll show how to made the necessary modifications which allow you to run a driver in this board.
After some experimenting with this board and comparisons with other boards, I saw that the the configuration of this board don't load the drivers at the boot time, not allowing you to run any peripheral device.
In a near future my goal is to push the modifications by default in the repository. But at the moment I think it's better to do the change manually.

1. We must go to nuttx/configs/olimex-stm32-e407/src/stm32_appinit.c and copy all the code.
2. In the same folder, create the file "stm32_bringup.c" and paste inside all the code.
3. Modify the name of the function from int board_app_initialize(uintptr_t arg) to int stm32_bringup().
4. Go to "stm32_boot.c". In the function void board_initialize(void) comment board_app_initialize() and add stm32_bringup().
5. Go to "Olimex-stm32-e407.h" and inside #ifndef __ASSEMBLY__ add int stm32_bringup(void);
6. Finally in Makefile, you must change this CSRCS = stm32_boot.c to this CSRCS = stm32_boot.c stm32_bringup.c

Once we have modify all the file, it's necessary to modify the configuration, so go to menuconfig and check the next things:
RTOS Features->RTOS Hooks->Custom board/driver initialization(Checked)-> Board Initialization thread (Checked)

If you don't do this modifications, the result that I receive it was that in some case (depending which thing I'm trying to run) some functionalities are still not initialize and crash or I try to initialize so late and I'm not been able to register the device.