It's not supported by driver anymore after using runtime pm
and there's no user of it, so delete it now.

Signed-off-by: Dong Aisheng <aisheng.dong@freescale.com>
Reviewed-by: Johan Derycke <johan.derycke@barco.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>