i3c: Correct reference to the I²C device data type

I²C peripheral devices that are connected to the controller are
represented in the Linux kernel as objects of the struct i2c_client.
Fix this in the header file.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230302161206.38106-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>