[9] RFR(S) 8184036: Restore -XX:UseAVX=3 as product value

[Vladimir Kozlov]

This is JDK 9 fix.

webrev: http://cr.openjdk.java.net/~kvn/8184036/webrev
https://bugs.openjdk.java.net/browse/JDK-8184036

After discussions we agreed that making -XX:UseAVX=3 experimental in 
JDK-8183103 changes was mistake.

Testing: RBT and jtreg on SKL machine with UseAVX=3.

Thanks,
Vladimir