gpu: nvgpu: drop user callback support in CE

Simplify the copyengine code by deleting support for the
ce_event_callback feature that has never been used. Similarly, create a
channel without the finish callback to get rid of that Linux dependency,
and delete the finish callback function as it now serves no purpose.

Delete also the submitted_seq_number and completed_seq_number fields
that are only written to.

Jira NVGPU-259

Change-Id: I02d15bdcb546f4dd8895a6bfb5130caf88a104e2
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1589320
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/mm/mm.c

@@ -259,12 +259,11 @@ void nvgpu_init_mm_ce_context(struct gk20a *g)
 #if defined(CONFIG_GK20A_VIDMEM)
 	if (g->mm.vidmem.size && (g->mm.vidmem.ce_ctx_id == (u32)~0)) {
 		g->mm.vidmem.ce_ctx_id =
-			gk20a_ce_create_context_with_cb(g,
+			gk20a_ce_create_context(g,
 				gk20a_fifo_get_fast_ce_runlist_id(g),
 				-1,
 				-1,
-				-1,
-				NULL);
+				-1);
 
 		if (g->mm.vidmem.ce_ctx_id == (u32)~0)
 			nvgpu_err(g,