[vector] RFR: Fix FMA intrinsic

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/panama/vector/fma/webrev.00/

There are 2 bug being fixed:
   (1) 3rd argument of a ternary operation is always null in 
intrinsified version;

   (2) VectorNode::make() accepts vector ops, but misses 
Op_FmaVF/Op_FmaVD in ternary case. Instead of adding them into the list, 
I propose to always pass scalar ops into the methods and get rid of the 
special cases for vector ops.

Thanks!

Best regards,
Vladimir Ivanov