media: ov5640: Use dev_fwnode() to obtain device's fwnode

Use dev_fwnode() on the device instead of getting an fwnode handle of the
device's OF node. The result is the same on OF-based systems and looks
better, too.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>