fix issue #315

[JarlEvanson]

This pull request should close #315.

[phil-opp]

Thanks a lot for tackling this! I saw that you also opened a PR on the uefi-rs repo to implement sorting the memory map: rust-osdev/uefi-rs#662. Given that this PR looks like it's closed to be merged, I wonder if it makes sense to wait for it instead of making our frame allocation more complex. What do you think?

[JarlEvanson]

I think that it makes sense to wait, rather than introducing more complexity.

[phil-opp]

Ok, thanks!

[phil-opp]

I just merged #360 to update the UEFI dependency to v0.20. We should now be able to use the new sort function.