i2c: designware: enable SLAVE in platform module

- Slave mode selected in platform module if the support is detected in
  the DT.

Signed-off-by: Luis Oliveira <lolivei@synopsys.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 64a39a9..7bfbcc6 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -228,6 +228,7 @@
  * @disable: function to disable the controller
  * @disable_int: function to disable all interrupts
  * @init: function to initialize the I2C hardware
+ * @mode: operation mode - DW_IC_MASTER or DW_IC_SLAVE
  *
  * HCNT and LCNT parameters can be used if the platform knows more accurate
  * values than the one computed based only on the input clock frequency.
@@ -282,6 +283,7 @@ struct dw_i2c_dev {
 	void			(*disable)(struct dw_i2c_dev *dev);
 	void			(*disable_int)(struct dw_i2c_dev *dev);
 	int			(*init)(struct dw_i2c_dev *dev);
+	int			mode;
 };
 
 #define ACCESS_SWAP		0x00000001