machine: add DMA support to spi tx

[sago35]

trafficstars

I made the call to SetupDMA() to use DMA to send. If no call is made, send it without DMA.

At the moment, it is wioterminal-only and most of the possible values cannot be set. The source code is messy and not clean. However, I think the future of effective use of the DMA can be examined on the basis of this PR.

• before (w/o DMA) : 40 - 42 fps
  • 5c85bbc6036ba84896f1332b6b52120c1107fb40
• after (with DMA) : 62 - 64 fps
  • 169aa2ac3675be0ff5b55d4b994e67cfc41d2fdd

[sago35]

ref: https://github.com/tinygo-org/drivers/pull/153#issuecomment-645390455

[aykevl]

I think we'll always want to use DMA. That is an easier to use API and likely faster overall.

[sago35]

I'm going to try and make it.

[sago35]

I plan to switch to the method used in the following PR.

#3985