video: tegra: nvmap: Add support for Serial Id feature

Add support for Serial Id feature which will be used by Nsight for
buffer tracking purpose. This feature expects a unique serial id per
buffer even if it is shared across multiple client processes.
Add following code:
- Create a new global counter field for serial id in nvmap device.
Initialize it to 0 when nvmap device is initialized.
- Introduce a new field for serial_id in nvmap_handle struct.
- When nvmap_handle is created, assign it's serial_id field with global
counter's value, and increment global counter.
- During NvRmMemQueryHandleParameters return this serial_id associated
with the handle.
- Do not decrement counter for serial_id even after freeing the handle.

Bug 4138373

Change-Id: Ic1fe22b082eefb352986f8fa44d4c38d186a366f
Signed-off-by: Ketan Patil <ketanp@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2918510
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/video/tegra/nvmap/nvmap_handle.c

@@ -77,6 +77,12 @@ void nvmap_handle_add(struct nvmap_device *dev, struct nvmap_handle *h)
 	rb_link_node(&h->node, parent, p);
 	rb_insert_color(&h->node, &dev->handles);
 	nvmap_lru_add(h);
+	/*
+	 * Set handle's serial_id to global serial id counter and then update the counter.
+	 * This operation is done here, so as to protect from concurrency issue, as we take
+	 * lock on handle_lock.
+	 */
+	h->serial_id = dev->serial_id_counter++;
 	spin_unlock(&dev->handle_lock);
 }