spi_get_timing() function

True if using GPIO matrix, or False if iomux pins are used.

Input delay from SCLK launch edge to MISO data valid.

Effective clock frequency (in Hz) from `spi_get_actual_clock()`.

Address of dummy bits used output. Set to NULL if not needed.

Address of cycles remaining (after dummy bits are used) output. - -1 If too many cycles remaining, suggest to compensate half a clock. - 0 If no remaining cycles or dummy bits are not used. - positive value: cycles suggest to compensate.