media: ov2740: Remove duplicative pointer in struct nvm_data

The struct i2c_client pointer is used only to get driver data,
associated with a struct device or print messages on behalf.
Moreover, the very same pointer to a struct device is already
assigned by a regmap and can be retrieved from there.
No need to keep a duplicative pointer.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>