drm/amdgpu: mark local function as static

Mark amdgpu_ras_debugfs_create_ctrl_node() as static.

Fixes: eb14235668777b ("drm/amdgpu: do not keep debugfs dentry")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c

@@ -1137,7 +1137,7 @@ static int amdgpu_ras_sysfs_remove_all(struct amdgpu_device *adev)
  *
  */
 /* debugfs begin */
-struct dentry *amdgpu_ras_debugfs_create_ctrl_node(struct amdgpu_device *adev)
+static struct dentry *amdgpu_ras_debugfs_create_ctrl_node(struct amdgpu_device *adev)
 {
 	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
 	struct dentry *dir;