microcode-20200609 release, intel-ucode 06-8e-0c/0x806ec revision=0xd6 causes freezes on warm boot

Per [debian bug 962757](https://bugs.debian.org/962757), [ubuntu bug 1883002](https://bugs.launchpad.net/bugs/1883002), and from internal testing, some systems are seeing freezes, particularly after warm reboots, with the 06-8e-0c/0x806ec revision 0xd6 from the 20200609 microcode release.

```
microcode: microcode updated early to revision 0xd6, date = 2020-04-23
microcode: sig=0x806ec, pf=0x80, revision=0xd6
```

The systems from the collected reports are:

Dell Latitude 7400, i5-8265U (debian bug)
Dell Latitude 7300, i7-8665U (ubuntu bug)
[Dell Latitude 5410, i5-8365U](https://certification.ubuntu.com/hardware/201911-27541)

Specifically, the reporter from ubuntu bug report inidats that they were initially affected by the similar issue against `0xca` as reported in #24; a BIOS update from Dell addressed that, but it was re-introduced with the 20200609 update that moved from `0xca` to `0xd6`. That users testing also indicated a much higher frequency of freezes occurring with warm reboots (the freeze seen with the third system was also after a warm reboot). The debian bug reported that their system was also stable with the `0xca` version but not the `0xd6` version.