[AVX512] Fix types for pshufd intrinsics. The immediate is the second argument...

[AVX512] Fix types for pshufd intrinsics. The immediate is the second argument and the mask is the 4th argument. Also move the 128/256 tests to the right test file.

Prior to this the immediate was a strange 16-bits and the 512-bit intrinsic couldn't receive the full 16 mask bits it needs.

llvm-svn: 269526