Sidecar FPFAs: pick up I2C SCL stretch fix (#1942)

Pickup
oxidecomputer/quartz@d4c2c02.

I'm updating the Front IO FPGAs as they're the primary thing impacted
here, but I'm also updating the mainboard FPGA as it has an I2C
interface to the Tofino 2.

The FPGAs are no longer built with Buildomat so I've updated their
READMEs accordingly. Additionally, I am pulling in an updated front IO
register map after the fix in
oxidecomputer/quartz@39d93cd
which results in a bunch of erroneous code getting pulled out of the
HTML file.

drv/sidecar-front-io/README.md

@@ -1,3 +1,2 @@
-`sidecar_qsfp_x32_controller.{bit, json, html, adoc}` are generated by
-[this build](https://github.com/oxidecomputer/quartz/runs/30559045709)
-([Buildomat link](https://buildomat.eng.oxide.computer/wg/0/details/01J8GXC3QJHXGHGZCMJJ6D5TKT/YlKXMfL6ScAyQhjBIstbaGiUUg1UrzPauEdXjjGVC0Z75WSp/01J8GXCRJWXD7KTN8N1RHNYAHF))
+`sidecar_qsfp_x32_controller.{bit, json, html, adoc}` are generated at
+[this commit](https://github.com/oxidecomputer/quartz/commit/d4c2c020ceff20e77dcae2c82af276f426cf0201)