sysutils/devcpu-data: Migrate our microcode update on Intel to use precreated files.

Intel provides prefabricated per-cpu microcode update files. We no longer need
a tool to extract them from the legacy microcode.dat store. This matches
what upstream linux distributions are doing now. Tested on my Intel machines
here and updates still succeed.

Reviewed by: swills cem
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D13921