Cosmo FPGA fix and feature rollup

[nathanaelhuffman]

• hubris/sp5 i2c deconfliction on boot. FPGA fixes properly address the muxing and prevent conflicts. Tested with over 200 boots. Cosmo intermittently shows 10 DIMMs instead of expected 12 (Cosmo, argon, EMY) quartz#434
• cosmo rev2+ UART rollback option. Users can fall back to the rev1 cosmo UART dongles using spare FPGA I/O by setting some registers manually. Helps setups that don't have the new UART dongles deployed.
• Fixes a pinout change coming in rev3 boards. Backwards compatible. Need to enable i2c mux for Cosmo C quartz#453
• Fixes rev2+ PG reporting due to rev2+ minor ethernet nic pinout changes, so pins are remapped correctly on rev2+ Cosmo-B re-mapped at least two power good signals to the sequencer FPGA quartz#444
• Provide additional espi features to support IPCC investigation. Also more aggressively clear down the IPCC fifos in A2 and upon espi_reset when booting to help mitigate a cosmo boot hang. Host SW has some additional driver improvements that provide the other half of the fix here, but no dependency between them.

Note that this rolls back #2287 which was a workaround for an FPGA issue that is resolved in this build. As noted above I have over 200 boot cycles with these two changes with no issues.

[labbott]

LGTM