Add 4FMA and 4VNNI instructions

[rsdubtso]

The two commits below

1. Add new instructions as described in https://software.intel.com/sites/default/files/managed/26/40/319433-026.pdf

2. Fix a typo leaf 7 CPUID detection

[herumi]

Thank you for fixing the bug about cpuid and a patch for AVX512_4FMAPS.
But I have a question. I do not know how to deal a new Op/En T1_4X for compressed displacement(disp8*N) such as v4fmaddps zmm1, zmm2, [rax + 64] and v4fmaddss xmm1, xmm2, [rax + 64]. Does 45906ae generate correct encoding for them?

[rsdubtso]

I've checked the encoding using an internal version of XED assembler/disassembler (part of Intel Software Development Emulator); unfortunately, the latest externally available version does not yet support the 4FMAPS and 4VNNI.

XED recognizes the compressed displacement encoding in the examples above as expected.

As a precaution, I can suggest keeping this PR open until Intel releases a public SDE version which supports the new instructions. I can post here once this happens and then you would be able to verify that the encoding is correct indeed.

I also want to thank you for an awesome tool. We are using it for MKL-DNN.

[herumi]

I see https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=47acf0bd9faef8634d242e19ec3b7f784d10ba76 and verified that xbyak generates expected encoding, then I merged it in master. Thank you for your feedback.

[herumi]

I renamed AVX512_4VNNI to AVX512_4VNNIW according Intel Architecture Instruction Set Extensions Programming Reference.

[rsdubtso]

Thanks. Yes, the 4VNNIW is the correct name.