[CFT] AMD cpu microcode update port sysutils/devcpu-data D13832

https://reviews.freebsd.org/D13832  <--- test this update

I'd like to get some feedback from AMD cpu users on this update.  I've
restructured and undone a few things that may have been keeping folks
using this port from getting their runtime cpu microcode updates.

After installing the port, grab your microcode version via
sysutils/x86info.  If you don't see an update, that only means there is
no update available for your system.

x86info -a | grep Microcode

Run the microcode_update and repeat.  Check /var/log/messages for a
notification that the code was updated.  You should be able to get
something like the following for your system if it executed an update:

root_at_lab:/home/sbruno # x86info -a | grep "CPU Model"
CPU Model (x86info's best guess): AMD FX Series Processor (OR-B2)

root_at_lab:/home/sbruno # x86info -a | grep Microcode
Microcode patch level: 0x6000629

root_at_lab:/home/sbruno # /usr/local/etc/rc.d/microcode_update onestart
Updating CPU Microcode...
Done.

root_at_lab:/home/sbruno # x86info -a | grep Microcode
Microcode patch level: 0x600063d

root_at_lab:/home/sbruno # grep microcode_update /var/log/messages
Jan 10 16:52:26 lab microcode_update:
/usr/local/share/cpucontrol/microcode_amd_fam15h.bin: updating cpu
/dev/cpuctl0 to revision 0x600063d... done.