media: ov5640: use JPEG mode 3 for 720p

Change 720p JPEG mode to mode 3 as per other resolutions.

Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>