[X86][SSE] Update MOVNTDQA non-temporal loads to generic implementation (LLVM)

MOVNTDQA non-temporal aligned vector loads can be correctly represented using generic builtin loads, allowing us to remove the existing x86 intrinsics.

Clang companion patch: D31766.

Differential Revision: https://reviews.llvm.org/D31767

llvm-svn: 300325