Port all other STM32H7 boards to Miosix 3. All untested.

miosix/arch/common/drivers/stm32f7_serial.cpp

miosix/arch/cortexM7_stm32h7/stm32h723zg_nucleo/boot.cpp

...cortexM7_stm32h7/stm32h723zg_nucleo/core/stage_1_boot.cpp

.../stm32h723zg_nucleo/interfaces-impl/arch_registers_impl.h

...rtexM7_stm32h7/stm32h723zg_nucleo/interfaces-impl/bsp.cpp

.../cortexM7_stm32h7/stm32h723zg_nucleo/stm32_1m+128k_rom.ld

miosix/arch/cortexM7_stm32h7/stm32h753xi_eval/boot.cpp

...h/cortexM7_stm32h7/stm32h753xi_eval/core/stage_1_boot.cpp

...h7/stm32h753xi_eval/interfaces-impl/arch_registers_impl.h

...cortexM7_stm32h7/stm32h753xi_eval/interfaces-impl/bsp.cpp

...ch/cortexM7_stm32h7/stm32h753xi_eval/stm32_2m+512k_rom.ld

miosix/config/Makefile.inc

...arch/cortexM7_stm32h7/stm32h723zg_nucleo/board_settings.h

...g/arch/cortexM7_stm32h7/stm32h753xi_eval/board_settings.h