reset: fix reset_control_lookup kerneldoc comment

Add a missing colon to fix a documentation build warning:

  ./include/linux/reset-controller.h:45: warning: Function parameter or member 'con_id' not described in 'reset_control_lookup'

Fixes: 6691dffa ("reset: add support for non-DT systems")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

include/linux/reset-controller.h

@@ -33,7 +33,7 @@ struct of_phandle_args;
  * @provider: name of the reset controller device controlling this reset line
  * @index: ID of the reset controller in the reset controller device
  * @dev_id: name of the device associated with this reset line
- * @con_id name of the reset line (can be NULL)
+ * @con_id: name of the reset line (can be NULL)
  */
 struct reset_control_lookup {
 	struct list_head list;