AP_Hal_ChibiOS: add support for ProfiLEDs

[IamPete1]

This adds support for ProfiLEDs building on #13535

ProfiLEDs require both a clock and data signal, this uses DMA so you can share a clock over channels in the same group. This adds support for both notify and scripting.

This moves round notify a little to use AP_SerialLED.

Works but needs some more testing.

[IamPete1]

This is a little demo of scripting with the LED - roll example and notify. They are a little flickery because notify and the script are sending the DMA at different times, all notify or all scripting and there is zero flicker. This show that both work in one vid tho.

https://www.youtube.com/watch?v=TiYbppn7EKs&feature=youtu.be

[IamPete1]

Have tested ProfiLEDs and NeoPixels from both Notify and Scripting