Porting SPI code from (Intel) Galileo to Edison - Arduino
You really need to determine whether all of that overshoot and ringing displayed on the scope is real, or just an artifact caused by how you're probing the circuit. I suspect it's the latter, so make sure you have a solid ground connection, your probes are properly compensated, and/or borrow/buy some better ones.

In general (ignoring the ringing and focusing on the underlying shape of the waveform), it looks like the Edison has a weaker clock driver than the Galileo, and in fact, it's so weak at 4 MHz that the overall amplitude is seriously reduced. If you're driving a relatively long or heavily-loaded bus, the Edison may need external buffers for the clock and MOSI lines.