[llvm] [X86] Recognise VPMADD52L pattern with AVX512IFMA/AVXIFMA (#153787) (PR #156714)

[Justin Riddell via llvm-commits]

Arghnews wrote:

Made change to early out if irregular vector size, and added test cases to cover it.

Note some cases do still generate vpmadd52 instructions, after operations to slice up the vector into regular sizes have been generated - I presume this is expected/fine

https://github.com/llvm/llvm-project/pull/156714