msm: camera: sensor: Power off the sensor if no gpios

Power off the sensor if no gpios at the time of power on, since
some regulator and clk need to be released.

Change-Id: Ie200459276b5327a1627e8839ec404c3c26f4205
Signed-off-by: Depeng Shao <depengs@codeaurora.org>
Signed-off-by: Jigarkumar Zala <jzala@codeaurora.org>