Jonathan Hogg 89945b1989 esp32/machine_hw_spi: Allow None for unused pins in initializer.
Make the hardware SPI initializer method match the `init()` method by 
allowing `None` to be given for `sck`/`mosi`/`miso` to specify an unused 
signal.
2021-06-17 18:52:22 +10:00
..
2021-05-20 23:22:03 +10:00