use the existing frequency from the spi object instead of hardcoded

[FoamyGuy]

This solves #8. We re-use the existing frequency on the spi object instead using the previously hard-coded value

[FoamyGuy]

tested on Itsy Bitsy M0 with this code:

import board
import busio
import digitalio
import adafruit_tlc59711
spi = busio.SPI(clock=board.SCK, MOSI=board.MOSI)

while not spi.try_lock():
    pass
spi.configure(baudrate=500000)
spi.unlock()
print("freq: {}".format(spi.frequency))
tlc59711 = adafruit_tlc59711.TLC59711(spi)
tlc59711[3] = (65535,0,65535)
print("freq: {}".format(spi.frequency))


while True:
    pass

Confirmed that the printed frequencies now always match whatever value you set in the first call to configure()

[kattni]

Thanks for the update!