USN-3531-2: Intel Microcode regression

USN-3531-1 updated Intel microcode to the 20180108 release. Regressions
were discovered in the microcode updates which could cause system
instability on certain hardware platforms. At the request of Intel, we have
reverted to the previous packaged microcode version, the 20170707 release.

Original advisory details:

It was discovered that microprocessors utilizing speculative execution
and branch prediction may allow unauthorized memory reads via sidechannel
attacks. This flaw is known as Spectre. A local attacker could use this to
expose sensitive information, including kernel memory. (CVE-2017-5715)

This update provides the microcode updates required for the corresponding
Linux kernel updates.