boards: st: Clean up nodes with status = "disabled"

- drop redundant board-level disables already handled in the SoC .dtsi

- document intentional disables (pin conflicts, optional peripherals

  and shared resources)

- fix DTS lint spacing warnings (stm32h747i_disco)

Signed-off-by: MBatuhan Altun <mbatuhanaltun3388@gmail.com>