Revert "mlx5e: Ensure rx timestamps are monotonically increasing"

This reverts commit ce33f96fcf2f2d0d49c406274bcc64df72fe530e.

It turns out that doing it this way did indeed prevent backwards
movement of timestamps, however it also lead to an ever increasing
error, eventually yielding timestamps hundreds or thousands of
seconds in the future.

Back this out until we can come up with a solution that prevents
backards timestamps and also avoids accumulating error.

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