media: ov5640: add missing output pixel format setting

The output pixel format changed by set_fmt() pad operation is not
correctly applied.  It is intended to be restored by calling
ov5640_set_framefmt() when the video stream is started.

However, when the device is powered on by s_power subdev operation before
the video stream is started, the current output mode setting is restored
by ov5640_restore_mode() that also clears pending_mode_change flag in
ov5640_set_mode().  So ov5640_set_framefmt() isn't called as intended and
the output pixel format is not restored.

This change adds the missing output pixel format setting in the
ov5640_restore_mode() that is called when the device is powered on.

Cc: Steve Longerbeam <slongerbeam@gmail.com>
Cc: Hugues Fruchet <hugues.fruchet@st.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>