[clang] Add _MM_FROUND_TO_NEAREST_TIES_EVEN to avx512fintrin.h (PR #99691)

[via cfe-commits]

hpkfft wrote:

Note that the following in xmmintrin.h
```
#define _MM_ROUND_NEAREST     (0x0000U)
#define _MM_ROUND_DOWN        (0x2000U)
#define _MM_ROUND_UP          (0x4000U)
#define _MM_ROUND_TOWARD_ZERO (0x6000U)
#define _MM_ROUND_MASK        (0x6000U)
```
sets different bits than the `_MM_FROUND_TO_*` naming scheme which is the subject of this patch.
The former applies to `_mm_getcsr()`; this patch applies to instruction intrinsics (`_mm512_add_round_ps`, etc.)


https://github.com/llvm/llvm-project/pull/99691