Two bugs with respect to the FMA instructions:
- the variant increment is supposed to be 0x10, not 0x01.
- the base opcode for scalar VFNMADD is 0x9d, not 0x9c
The Perl script which auto-generated the VFM instructions had
incorrectly conflated the VEX.W and VEX.L bits, with the result that
only half the valid instructions were generated.