gpu: nvgpu: track dev nodes using dynamic linked list

Remove static dev node meta data from struct nvgpu_os_linux and replace
it by a dynamic list. Struct nvgpu_os_linux will only keep track of list
head and number of entries.

Add new structure nvgpu_cdev to store meta data of each dev node and
create/setup it dynamically in gk20a_user_init(). Once done, add the new
node under list head maintained in nvgpu_os_linux.

Add a static list dev_node_list[] that contains list of dev node names
and file operations. This static list is used to create nvgpu_cdev data
structures and to register new device nodes.

Update all dev node open file operations (e.g. gk20a_as_dev_open()) to
extract struct gk20a pointer from device pointer of dev node.
gk20a device is the parent of dev node device.

Jira NVGPU-5648

Change-Id: If070c3428afd6215e45b4919335d9f43e04c36f9
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2428500
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

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

@@ -466,13 +466,12 @@ free_ref:
 
 int nvgpu_ioctl_tsg_dev_open(struct inode *inode, struct file *filp)
 {
-	struct nvgpu_os_linux *l;
 	struct gk20a *g;
 	int ret;
+	struct nvgpu_cdev *cdev;
 
-	l = container_of(inode->i_cdev,
-			 struct nvgpu_os_linux, tsg.cdev);
-	g = &l->g;
+	cdev = container_of(inode->i_cdev, struct nvgpu_cdev, cdev);
+	g = get_gk20a(cdev->node->parent);
 
 	nvgpu_log_fn(g, " ");
 
@@ -482,7 +481,7 @@ int nvgpu_ioctl_tsg_dev_open(struct inode *inode, struct file *filp)
 		return ret;
 	}
 
-	ret = nvgpu_ioctl_tsg_open(&l->g, filp);
+	ret = nvgpu_ioctl_tsg_open(g, filp);
 
 	gk20a_idle(g);
 	nvgpu_log_fn(g, "done");