Issue: Configuring the frame length to certain values causes incorrect
operation.
Symptoms: Certain frame lengths result in the master sending one extra
clock pulse. The slave device may then become desynchronized.
Workaround: The following frame lengths are supported and can be used.
Do not use other frame lengths.
* Serial mode: 0, 2, 4, 6, 8
* Dual mode: 0, 1, 3, 5, 7, 8
* Quad mode: 0, 1, 2, 3, 5, 6, 7, 8