It seems like this might not get fixed. There are some related bugs that after looking into it, seem to be similar and probably are. No one seems to believe that it's a problem though. Quite frankly, if only a touchpad is generating that many interrupts and not a mouse of other things, then it seems to me that there is a problem with the driver.
Looking at the upstream bug report (link) it seems to be an hardware constraint, so there is nothing we can do to fix the problem.