regulator: Fix regulator_register() API signature in Documentation

The commit 2c043bcbf287 ("regulator: pass additional of_node to
regulator_register()") added an additional parameter to the
regulator_register() API.
Update the Documentation accordingly to reflect the change
in the function signature.

Reported-by: Thomas Abraham <[e-mail]>
Signed-off-by: Rajendra Nayak <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/power/regulator/regulator.txt

···
 
 struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
 	struct device *dev, struct regulator_init_data *init_data,
-	void *driver_data);
+	void *driver_data, struct device_node *of_node);
 
 This will register the regulators capabilities and operations to the regulator
 core.