I2C4 AF Pin Mapping Updates

[stephenhensley]

I'm working on a project that uses the H7 with a few new pins, and they don't map to the existing fixed-AF mapping based on peripheral selection.
IIRC there may also have been an existing issue with using I2C4 with some of the pins available on the Seed.

This update adds a pin map to the i2c peripheral containing the Alternate functions for all supported pins (and the ones I'm using.

Things to do before merging:

• Merge the UART logging and/or rebase so this is only the I2C changes..
• Double check all valid I2C pins for Seed, Seed2 DFM, and PatchSM are covered within the new map (I only checked through the Seed datasheet so far).

I observed about 1kB increase in binary size after this update. The new mapping is set up to be constexpr, but the typical usage patterns involve runtime Config structs. So in most existing uses it won't qualify for finding them at compile time.

[github-actions]

Test Results

167 tests  ±0   167 ✅ ±0   0s ⏱️ ±0s
  1 suites ±0     0 💤 ±0 
  1 files   ±0     0 ❌ ±0 

Results for commit 3bdb835. ± Comparison against base commit 24be4af.

♻️ This comment has been updated with latest results.