media: ov2740: Improve ov2740_check_hwcfg() error reporting

Make ov2740_check_hwcfg() report an error on failure in all error paths,
so that it is always clear why the probe() failed.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>