gpu: nvgpu: allocate object context for specific GR instance

Add new API nvgpu_get_gpu_instance_id_from_cdev() that returns GPU
instance id from nvgpu_cdev pointer.

Store cdev pointer in channel private data channel_priv and ctrl node
private data gk20a_ctrl_priv.

Update below functions to pass cdev pointer :
__gk20a_channel_open()
gk20a_channel_open_ioctl()

In gk20a_channel_ioctl(), extract gpu instance id using cdev pointer
stored in channel_priv and new API nvgpu_get_gpu_instance_id_from_cdev().
Extract GR instance id using nvgpu_grmgr_get_gr_instance_id()

Invoke context creation API inside nvgpu_gr_exec_with_err_for_instance()
so that context is created with correct GR instance id.

Jira NVGPU-5648

Change-Id: I5a4e79165e021b56181d08105b2185306a19703b
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2435465
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: Lakshmanan M <lm@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.c

@@ -558,3 +558,15 @@ fail:
 	gk20a_user_deinit(dev);
 	return err;
 }
+
+u32 nvgpu_get_gpu_instance_id_from_cdev(struct gk20a *g, struct nvgpu_cdev *cdev)
+{
+	struct nvgpu_cdev_class_priv_data *priv_data;
+
+	if (nvgpu_is_enabled(g, NVGPU_SUPPORT_MIG)) {
+		priv_data = dev_get_drvdata(cdev->node);
+		return priv_data->local_instance_id;
+	}
+
+	return 0;
+}