Ebony is inherently a "loose grain" dense wood, which at first thought sounds counter to the term dense wood. Although a heavy wood it has a porous surface structure unless properly scrapped as sanding does no good.

What I see are specks of normal dust embedded into the voids (microscopic in nature mostly) and accumulated into visible 'white spots'. If you carefully take a soft cloth like a microfiber one ( doesn't usually leave any lint behind) and apply some alcohol and clean the surface you can eliminate many of those from it.

Careful using alcohol as a drop on the varnish finish can and many times will leave a spot and touching it will ruin the finish as the alcohol acts like a solvent on it.

Not much else you can do. It does not affect the sound at all and I seriously doubt you can 'feel' it with your finger as it's played.