Added GPU local wait to load balancing

The GPU local wait time was not included in the load imbalance timing.
This could lead to incorrect load imbalance reporting and dynamic
load balancing, especially with CUDA stream priorities.
Note that we can't accurately measure the GPU time, when it finishes
during dd_move_f.

Change-Id: If4bb0f867593450cc025c8593672b0569397b1d6