Add GPDMA API. Should go in libopencm3 when it's more fleshed-out.
Add SGPIO DMA configuration code.
Modified ldscripts to more accurately represent LPC4330 hardware.
Moved M0 RAM from local to AHB.
Created separate region for sleep RAM.
Extract/isolate path details in Makefile_inc.mk.
Add SGPIO configuration to support GPDMA interrupts.
Bracket SGPIO GPDMA slice configuration with multislice==false test. It only makes sense in single slice mode (until I have a clever idea for doing GPDMA with multiple slices).
Extract SGPIO multi_slice configuration argument into an init-time function, so it doesn't need to be passed each time the SGPIO interface direction is changed.
Move LLI_COUNT constant out of SGPIO DMA utility functions.
Change SGPIO DMA configuration API from dividing up a buffer's length into M parts to creating a chain of M transfers of size N.
Remove irrelevant assumption that LLI argument is a pointer to an array.
Rename SGPIO DMA internal function to match style of public functions.
Expose SGPIO DMA LLI configuration function.
Remove LLI declarations internal to SGPIO DMA module.
Require a start LLI for SGPIO DMA start functions.