MacPro7,1 memory configuration workaround is inadequate

*Guide*: OpenCore Post Install Guide ([link](https://dortania.github.io/OpenCore-Post-Install/universal/memory.html#mapping-our-memory))

- Firstly, you can always use RestrictEvents. It is very simple and resolves the issue in an elegant way.
- Secondly, I checked the framework and discovered that you can provide proper empty slots by giving them `NO DIMM` value in `Manufacturer` field. See [this update](https://github.com/acidanthera/OpenCorePkg/commit/5db7147293e952fbdd9c3168631b0f75a9c09b81#diff-ff76194142498a223908566484df3ed947764eace1ae6104347516807422c9acR5332-R5346).

For the second route it is much better to just craft proper 4 sticks via `CustomMemory` than do what is advised. If you have just two sticks, you can make 4 halving the size of each.