liverpool: free the frames of nested indirect buffer tasks (#5258)

* liverpool: free the frames of nested indirect buffer tasks

IndirectBuffer (graphics and compute) and IndirectBufferConst run their
target as a nested coroutine and wait for it to finish, but the finished
task stays suspended at final_suspend and its frame is never destroyed.
Every indirect buffer leaked about 600 bytes of host heap.

In inFAMOUS Second Son that is ~440 nested tasks per second, so committed
memory grew by ~15 MB per minute (~0.9 GB per hour) without bound. With
the frames destroyed it stays flat after warm-up.

* liverpool: drop comments on nested task destroy

src/video_core/amdgpu/liverpool.cpp

@@ -205,6 +205,7 @@ Liverpool::Task Liverpool::ProcessCeUpdate(std::span<const u32> ccb) {
                 YIELD_CE();
                 RESUME_CE(task);
             }
+            task.handle.destroy();
             break;
         }
         default:
@@ -801,6 +802,7 @@ Liverpool::Task Liverpool::ProcessGraphics(std::span<const u32> dcb, std::span<c
                     YIELD_GFX();
                     RESUME_GFX(task);
                 }
+                task.handle.destroy();
                 break;
             }
             case PM4ItOpcode::IncrementDeCounter: {
@@ -935,6 +937,7 @@ Liverpool::Task Liverpool::ProcessCompute(std::span<const u32> acb, u32 vqid) {
                 YIELD_ASC(vqid);
                 RESUME_ASC(task, vqid);
             }
+            task.handle.destroy();
             break;
         }
         case PM4ItOpcode::DmaData: {