Fix all the current issues with the AArch64 register cache.
Fixes all the current issues I've been experiencing.
Scaled back the register cache idea for now so I can actually work on some real instructions.

Tested this work with unit tests so I know it works.
Unit tests are pretty great things.
Merge pull request #1065 from Sonicadvance1/AArch64-fix-regcache

Fix all the current issues with the AArch64 register cache.