media: i2c: ov9282: remove unused and unset i2c_client member

This is not need anyway as the i2c_client is stored in v4l2_subdev.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>