Testing w/o DMA
Fix SPI_SPEED_20MHZ
Add GPIO pin ranges
Initial implementation of spiInternalInitStream and spiSequenceStart
(mode, speed set up, based on STM32/bus_spi_ll.c)
spiCalculateDivider records numbers as calculated in pico-sdk spi_set_baudrate,
for use later in spiCalculateClock.
* PICO changes
* Spelling corrected in API v2
* Corrected as per @ledvinap - granted will be generated in future.
* As per @tstibor
* Correction and comment as per @ledvinap