gpu: nvgpu: emphasize fence syncpt/sema interfaces

Sometimes the syncpt-based fences are not used, and often the sema-based
fences are not used. Move code around to new files to make it easier to
see what happens and to allow leaving code out of the build easily.

Start using nvgpu_fence_ops::free again and move the fence release
there. The syncpt data is not refcounted, so it doesn't have this.

Jira NVGPU-5773

Change-Id: I991f91886c59cf2c2fbfd2e75305ba512b5d7371
Signed-off-by: Konsta Hölttä <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2395069
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svc-mobile-misra <svc-mobile-misra@nvidia.com>
Reviewed-by: svc-mobile-cert <svc-mobile-cert@nvidia.com>
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
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drivers/gpu/nvgpu/common/sync/channel_sync_syncpt.c

@@ -40,6 +40,7 @@
 #include <nvgpu/channel_sync_syncpt.h>
 #include <nvgpu/priv_cmdbuf.h>
 #include <nvgpu/fence.h>
+#include <nvgpu/fence_syncpt.h>
 #include <nvgpu/string.h>
 
 #include "channel_sync_priv.h"