[TARGET_STM32F4] new structure for F407 and F429 targets -part1

move specific files from old position into new target folders under
target_stm32f4
[TARGET_STM32F4] new structure for F407 and F429 targets - part2

remove target_stm32f407vg files
[TARGET_STM32F4] new structure for F407 and F429 targets - part3

remove target_stm32f429zi files
[TARGET_STM32F4] new structure for F407 and F429 targets - part4

Solves the problem NULL -> HAL_NULL for the additional hw blocks in the
larger mcus.

For F401 and F411 this was already solved in #596.
Merge pull request #639 from ohagendorf/bcostm_branch_f4xx_structure_reorder

Targets: Nucleo F4xx - Reorder f4xx structure