Remove a global debugfs variable and instead save the allocator
debugfs root node in the gk20a struct.
Bug 1799159
Change-Id: If4eed34fa24775e962001e34840b334658f2321c
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1225611
(cherry picked from commit 1908fde10bb1fb60ce898ea329f5a441a3e4297a)
Reviewed-on: http://git-master/r/1242390
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>