regulator: consumer: Supply missing prototypes for 3 core functions

regulator_suspend_enable(), regulator_suspend_disable() and
regulator_set_suspend_voltage() are all exported members of the
API, but are all missing prototypes.

Fixes the following W=1 warning(s):

 drivers/regulator/core.c:3805:5: warning: no previous prototype for ‘regulator_suspend_enable’ [-Wmissing-prototypes]
 3805 | int regulator_suspend_enable(struct regulator_dev *rdev,
 | ^~~~~~~~~~~~~~~~~~~~~~~~
 drivers/regulator/core.c:3812:5: warning: no previous prototype for ‘regulator_suspend_disable’ [-Wmissing-prototypes]
 3812 | int regulator_suspend_disable(struct regulator_dev *rdev,
 | ^~~~~~~~~~~~~~~~~~~~~~~~~
 drivers/regulator/core.c:3851:5: warning: no previous prototype for ‘regulator_set_suspend_voltage’ [-Wmissing-prototypes]
 3851 | int regulator_set_suspend_voltage(struct regulator *regulator, int min_uV,
 | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200625163614.4001403-2-lee.jones@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/consumer.h

@@ -32,10 +32,12 @@
 #define __LINUX_REGULATOR_CONSUMER_H_
 
 #include <linux/err.h>
+#include <linux/suspend.h>
 
 struct device;
 struct notifier_block;
 struct regmap;
+struct regulator_dev;
 
 /*
  * Regulator operating modes.
@@ -277,6 +279,14 @@ int regulator_unregister_notifier(struct regulator *regulator,
 void devm_regulator_unregister_notifier(struct regulator *regulator,
 					struct notifier_block *nb);
 
+/* regulator suspend */
+int regulator_suspend_enable(struct regulator_dev *rdev,
+			     suspend_state_t state);
+int regulator_suspend_disable(struct regulator_dev *rdev,
+			      suspend_state_t state);
+int regulator_set_suspend_voltage(struct regulator *regulator, int min_uV,
+				  int max_uV, suspend_state_t state);
+
 /* driver data - core doesn't touch */
 void *regulator_get_drvdata(struct regulator *regulator);
 void regulator_set_drvdata(struct regulator *regulator, void *data);