Remove static variable gk20a_device which held a pointer
to struct device. nvgpu can serve multiple GPUs, so a
static pointer does not work.
Change-Id: I79faf5c26658490c955a9b15137e5f671650fd28
Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-on: http://git-master/r/1123940
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>