Stop video streaming when requested.

When s_stream is called to stop the video streaming, if/else condition calls
start_streaming function instead of the one for stopping it.

Fixes: 43619059 ("media: imx214: Add imx214 camera sensor driver")
Signed-off-by: Daniel Gomez <daniel@qtec.com>
Signed-off-by: Ricardo Ribalda <ribalda@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>