media: ov5640: do not change mode if format or frame interval is unchanged

Save load of mode registers array when V4L2 client sets a format or a
frame interval which selects the same mode than the current one.

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>