Convert drivers/gpu/drm class to use dev_pm_ops for power management and
remove Legacy PM ops hooks. With this change, drm class registers
suspend/resume callbacks via class->pm (dev_pm_ops) instead of Legacy
class->suspend/resume. When __device_suspend() runs call-backs, it will
find class->pm ops
Convert drivers/gpu/drm class to use dev_pm_ops for power management and
remove Legacy PM ops hooks. With this change, drm class registers
suspend/resume callbacks via class->pm (dev_pm_ops) instead of Legacy
class->suspend/resume. When __device_suspend() runs call-backs, it will
find class->pm ops
