i2c: Drop i2c_adapter.id

There is no user left of i2c_adapter.id, so we can get rid of it.
Finally! :)

Signed-off-by: Jean Delvare <khali@linux-fr.org>

include/linux/i2c.h

@@ -353,7 +353,6 @@ struct i2c_algorithm {
  */
 struct i2c_adapter {
 	struct module *owner;
-	unsigned int id __deprecated;
 	unsigned int class;		  /* classes to allow probing for */
 	const struct i2c_algorithm *algo; /* the algorithm to access the bus */
 	void *algo_data;