Fix Errors in Flags Test ROM

We are still failing some checks from the [flags test ROM](https://github.com/Timendus/chip8-test-suite) 

```
   -= T E S T  R O M  R E S U L T S =-

??? (corrupted text lol)
3 3/3
4 4/4
5 2/4*
6 3/3
7 3/4*
E 3/3
CARRY
4 2/4*
5 3/4*
6 3/3
7 4/4
E 3/3
OTHER
FE 2/2
```