Sidecar: Update FPGA to Quartz 8a2c75a (#1901)

Pulling in an update to the Sidecar mainboard FPGA which adds a debounce
to the PCIe PERST signal from the host. Details in
oxidecomputer/quartz@8a2c75a.

There's a significant amount of code deletion from the register map HTML
because I fixed a template bug that was generating a bunch of junk table
rows. Those are gone now!

drv/sidecar-mainboard-controller/README.md

@@ -1,5 +1,5 @@
 `sidecar_mainboard_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))
+[this build](https://github.com/oxidecomputer/quartz/runs/31265313143)
+([Buildomat link](https://buildomat.eng.oxide.computer/wg/0/details/01J9Q7KSB2X8WNJW87JEK4HNE6/T8sUhiSCg71FtHIbbuUCp5gbIcECXolhYjLOzB89gimJLmc2/01J9Q7M1RW0JRP3R0S6Y75F4EJ))
 
 If you updated these artifacts you probably want to update `drv-ignition-api` as well.