media: ov5640: fix mode change regression

fixes: 6949d864 ("media: ov5640: do not change mode if format or frame interval is unchanged").

Symptom was fuzzy image because of JPEG default format
not being changed according to new format selected, fix this.
Init sequence initialises format to YUV422 UYVY but
sensor->fmt initial value was set to JPEG, fix this.

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>