In the top left, there should be a "changes from..." drop down menu that will let you choose which commits you want to view. The default is "changes from all commits".
If you're on GitHub Enterprise, availability will depend on the last time your company has installed updates.
That is not the same feature.
It requires you to always add your fix in a new commit add opposed to amending the commits and maintain a clear purposed commit list.
I think the more official Git way of doing it would be to collect all the changes in separate commits, and then squash merge them at the end of the code review.