AVX512: Add vpmovzxbw/d/q ,vpmovzxw/d/q ,vpmovzxbdq lowering patterns that...

AVX512: Add vpmovzxbw/d/q ,vpmovzxw/d/q ,vpmovzxbdq lowering patterns that support 256bit inputs like AVX patterns ( that are disable in case HasVLX , see SS41I_pmovx_avx2_patterns).

Differential Revision: http://reviews.llvm.org/D17504

llvm-svn: 261724