media: ov5640: fix exposure regression

Symptom was black image when capturing HD or 5Mp picture
due to manual exposure set to 1 while it was intended to
set autoexposure to "manual", fix this.

Fixes: bf4a4b51 ("media: ov5640: Don't force the auto exposure state at start time").

Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>