It's certainly not "completely outside of the scope of parliamentary power", given that the constitutional convention in the UK is based on parliamentary supremacy, but it's also the case that prorogation being formally a prerogative of the Queen, her consent would have to be obtained to discuss any legislation, which in practice means the consent of the government. Of course, in usual circumstances, the government [also] commands a majority in parliament...
What this means in the current circumstances is that BoJo has a (de facto) veto on such a law.
For some example when such a change to a royal prerogative did happen, the Fixed Term Parliaments Act 2011 abolished the monarch's (effectively, the government's) power to dissolve Parliament at will, which until then was also a royal prerogative. But this Act left prorogation untouched.
As an example when the government exercised its (de facto) veto over a royal prerogative
In 1999, Queen Elizabeth II, acting on the advice of her British Cabinet, refused to signify her consent to the Parliament of the United Kingdom debating the Military Action Against Iraq (Parliamentary Approval) Bill, which sought to transfer from the sovereign to parliament the power to authorize military strikes against Iraq.
As Jotia points out in a comment below, the official language is that the monarch "signifies" (gives) or doesn't give her consent "on the advice of" minsters. In practice, that means the government has this power. I think last time a monarch's representative refused to follow such "advice" was the King–Byng affair in Canada, in the 1920s.