Add gpu_mem/gpu_mem_total to the atrace gfx and memory categories

Permission was added in I0808d8fe6a8416534fbec5a273d668700f0f7129.

Bug: 168902332
Test: take a systrace with gfx/memory/both and check ftrace enablement
Change-Id: I66253c54ce7a29f1fe051925ca00e6bd7c0def86