gpu: nvgpu: move cyclestats_snapshot data to struct gk20a

cyclestats_snapshot data and lock is right now stored in struct nvgpu_gr
Use case itself is not specific to GR engine but in general it applies
to other units outside of GR too.

Hence it makes sense to move both data and lock to struct gk20a instead
of keeping them in struct nvgpu_gr

Update all cyclestats_snapshot code to refer data/lock from struct gk20a
Remove gr_priv.h header include from cyclestats_snapshot.c

Some of the functions were mistakenly declared in gr_gk20a.h.
Move them to cyclestats_snapshot.h and rename them to form nvgpu_css_*()

Jira NVGPU-1103

Change-Id: I3fb32fe96f0ca6613f4640c8bd227b9e0e02dca3
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2104848
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/os/linux/module.c

@@ -50,6 +50,7 @@
 #include <nvgpu/channel.h>
 #include <nvgpu/gr/gr.h>
 #include <nvgpu/pmu/pmu_pstate.h>
+#include <nvgpu/cyclestats_snapshot.h>
 
 #include "common/gr/gr_priv.h"
 #include "platform_gk20a.h"
@@ -779,6 +780,10 @@ void gk20a_remove_support(struct gk20a *g)
 			sim_linux->remove_support_linux(g);
 	}
 
+#if defined(CONFIG_GK20A_CYCLE_STATS)
+	nvgpu_free_cyclestats_snapshot_data(g);
+#endif
+
 	nvgpu_remove_usermode_support(g);
 
 	nvgpu_free_enabled_flags(g);