On PPC we don't have the `ties to even` FP roundings enabled,
therefore their equivalent Simd op will never get emitted.

Once support is added, the flag needs to be set under
`SupportedMachineOperatorFlags` within the instruction selector.
Setting this flag affects both the scalar and Simd variants
of this op.

Change-Id: I7d486def103045d2dee7cb691927feb19c3e5ef4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2996747Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#75528}