Move i2c to mod, split device and controller
Remove mode generic:
I don't think it's reasonable to use the i2c in device mode while
blocking, so I'm cutting the generic.
GP29 is connected to the cyw43 SCK pin. cyw43 is selected by
default (due to rp2040 pins being input/pulldown by default), so the
wifi chip is always selected and watches the SCK pin. this little bit of
load on the SCK pin is enough to disturb the 300k voltage divider used
for VSYS sensing, making the test flaky.
with uniform treatment of adc inputs it's easy enough to add a new
sampling method. dma sampling only supports one channel at the moment,
though round-robin sampling would be a simple extension (probably a new
trait that's implemented for Channel and &[Channel]). continuous dma as
proposed in #1608 also isn't done here, we'd expect that to be a
compound dma::Channel that internally splits a buffer in half and
dispatches callbacks or something like that.
this lets us treat pins and the temperature sensor uniformly using the
same interface. uniformity in turn lets us add more adc features without
combinatorial explosion of methods and types needed to handle them all.
this removed the RelocatedProgram construction step from pio uses.
there's not all that much to be said for the extra step because the
origin can be set on the input program itself, and the remaining
information exposed by RelocatedProgram can be exposed from
LoadedProgram instead (even though it's already available on the pio_asm
programs, albeit perhaps less convenient). we do lose access to the
relocated instruction iterator, but we also cannot think of anything
this iterator would actually be useful for outside of program loading.
