MAX32666: incorrect comment in MXC_SPI_SetRXThreshold() docstring

[JordanAceto]

The docstring for MXC_SPI_SetRXThreshold(spi, numBytes) says that the number of bytes parameter must be between [0, 8] inclusive, but the actual range is [0, 30].

Docstring here: https://github.com/analogdevicesinc/msdk/blob/74a552e8c7d9570243def76250657831aa6bb7ca/Libraries/PeriphDrivers/Include/MAX32665/spi.h#L406-L420

Actual check here: https://github.com/analogdevicesinc/msdk/blob/74a552e8c7d9570243def76250657831aa6bb7ca/Libraries/PeriphDrivers/Source/SPI/spi_reva1.c#L632-L636