boards: stm32: Move STM32 boards SPI pin configuration to device tree

Move SPI pin configuration to device tree for all STM32 based
boards.
This should not bring any change in pin configuration.

Though, some adjuments have been made on following boards for
coherency:

* b_l4s5i_iot01a1: Removed "very-high-speed" on SPI3 MOSI pin.
Tested with no impact.
* black_f407zg_pro: SPI1 pins configured but not SPI1 node.
Removed pin config as not documented neither.
* sensortile_box: SPI2 pins configured but not SPI2 node.
Removed pin config as not documented neither.
* nucleo_g431rb/nucleo_g474re/nucleo_l476rg/nucleo_l4r5zi:
SPI2 and SPI3 pins were configured but missing.
Added since they were documented.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>