media: i2c: ov13b10: Improve code readability

Use mode instead of ov13b->cur_mode in set_pad_format.

Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Hao Yao <hao.yao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
[hverkuil: fix typo: redability -> readability]