GPU sync problem

[Amjad50]

When was working on MDEC (#15), there was an issue when testing with the mdec test from JaCzekanski_tests.

The issue is that the gpu DMA (2), would hang in the middle, because it would set the CPUtoVRAM blit command, and then the flag READY_FOR_CMD_RECV should be cleared, but because we are doing it in another thread, there seems to be a delay after the command is written to the GPU and the flag being cleared.
Not sure why, but the test rom will hang (maybe bug in the library that handles GPU DMA), but the GPU sync should be fixed anyway this will help make the GPU more accurate and hopefully fixes more bugs (#7 ?)

[Amjad50]

After fixing the issue, the main issue was with the flag DMA_DIRECTION being out of sync