Fix gsp synch

Fixed various issues with GSP synchronization. These include:
* Fixed a bug where the command list size was being incorrectly decoding, causing the GPU to execute invalid commands.
* Triggering the various GSP interrupts at more appropriate times.
* Setting an expected return code for RegisterInterruptRelayQueue.
Can you add a comment in the header definining the `size` member and stating in which units it is measured in? (and if we're still unsure about what the actual units are, add a TODO about it as well)