rnndb/graph/tpc: document MP.PM_CTRL for GK20A
rnndb/graph/tpc: document MP.PM_CTRL for GK20A

Taken out from:
https://android.googlesource.com/kernel/tegra/+/b445e5296764d18861a6450f6851f25b9ca59dee/drivers/video/tegra/host/gk20a/hw_gr_gk20a.h

MoochMcGee/envytools,kfractal/envytools,karolherbst/envytools,hakzsam/envytools,hakzsam/envytools,hakzsam/envytools,envytools/envytools,MoochMcGee/envytools,pierremoreau/envytools,MoochMcGee/envytools,MoochMcGee/envytools,grate-driver/envytools,karolherbst/envytools,kfractal/envytools,hakzsam/envytools,envytools/envytools,envytools/envytools,karolherbst/envytools,pierremoreau/envytools,pierremoreau/envytools,pierremoreau/envytools,pierremoreau/envytools,grate-driver/envytools,envytools/envytools,grate-driver/envytools,hakzsam/envytools,karolherbst/envytools,kfractal/envytools,kfractal/envytools,karolherbst/envytools,envytools/envytools,grate-driver/envytools,MoochMcGee/envytools,kfractal/envytools,grate-driver/envytools