spectre v2 microcodes blacklist (march update)

[Alexander Sergeyev]

Hi,

the microcode revision guidance from Intel is revised once again [1] (1 Mar).

It looks like the following:

> Intel document only clears the 0xc2 microcode on *some* parts with CPUID 506E3 
> (INTEL_FAM6_SKYLAKE_DESKTOP stepping 3). For the Skylake H/S platform it's OK 
> but for Skylake E3 which has the same CPUID it isn't (yet) cleared.

is no longer a problem. CPUID 506E3 with both Skylake H/S and Skylake Xeon E3 
is labelled as "production" now.

Could we drop { INTEL_FAM6_SKYLAKE_DESKTOP, 0x03, 0xc2 } from 
spectre_bad_microcodes?

[1] 
https://newsroom.intel.com/wp-content/uploads/sites/11/2018/03/microcode-update-guidance.pdf