i2c: Only include slave support if selected

Make the slave support depend on CONFIG_I2C_SLAVE. Otherwise it gets
included unconditionally, even when it is not needed.

I2C bus drivers which implement slave support must select
I2C_SLAVE.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index e3a1721..7c76959 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -228,7 +228,9 @@
 	struct device dev;		/* the device structure		*/
 	int irq;			/* irq issued by device		*/
 	struct list_head detected;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
 	i2c_slave_cb_t slave_cb;	/* callback for slave mode	*/
+#endif
 };
 #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
 
@@ -253,6 +255,7 @@
 
 /* I2C slave support */
 
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
 enum i2c_slave_event {
 	I2C_SLAVE_REQ_READ_START,
 	I2C_SLAVE_REQ_READ_END,
@@ -269,6 +272,7 @@
 {
 	return client->slave_cb(client, event, val);
 }
+#endif
 
 /**
  * struct i2c_board_info - template for device creation
@@ -404,8 +408,10 @@
 	/* To determine what the adapter supports */
 	u32 (*functionality) (struct i2c_adapter *);
 
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
 	int (*reg_slave)(struct i2c_client *client);
 	int (*unreg_slave)(struct i2c_client *client);
+#endif
 };
 
 /**