[SKX] Extended non-temporal load/store instructions for AVX512VL subsets.

Added avx512_movnt_vl multiclass for handling 256/128-bit forms of instruction.
Added encoding and lowering tests.

Reviewed by Elena Demikhovsky <elena.demikhovsky@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215536 91177308-0d34-0410-b5e6-96231b3b80d8