nvgpu_device_get can return NULL if supplied invalid ID or instance
ID. We expect GR device struct to be non-NULL there hence just
assert that it is indeed non-NULL in gr_reset_engine and
ga10b_grmgr_init_gr_manager.
CID 224133
CID 250232
Bug 3512546
Change-Id: Id09a1c436a8e49b921111b940d3d013bd66bff7a
Signed-off-by: Sagar Kamble <skamble@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2707018
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>