regulator: rk808: Fix sparse non static symbol warnings

Fixes the following sparse warnings:

drivers/regulator/rk808-regulator.c:100:5: warning:
 symbol 'rk808_set_suspend_voltage' was not declared. Should it be static?
drivers/regulator/rk808-regulator.c:115:5: warning:
 symbol 'rk808_set_suspend_enable' was not declared. Should it be static?
drivers/regulator/rk808-regulator.c:126:5: warning:
 symbol 'rk808_set_suspend_disable' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/rk808-regulator.c

@@ -97,7 +97,7 @@ static int rk808_set_ramp_delay(struct regulator_dev *rdev, int ramp_delay)
 				  RK808_RAMP_RATE_MASK, ramp_value);
 }
 
-int rk808_set_suspend_voltage(struct regulator_dev *rdev, int uv)
+static int rk808_set_suspend_voltage(struct regulator_dev *rdev, int uv)
 {
 	unsigned int reg;
 	int sel = regulator_map_voltage_linear_range(rdev, uv, uv);
@@ -112,7 +112,7 @@ int rk808_set_suspend_voltage(struct regulator_dev *rdev, int uv)
 				  sel);
 }
 
-int rk808_set_suspend_enable(struct regulator_dev *rdev)
+static int rk808_set_suspend_enable(struct regulator_dev *rdev)
 {
 	unsigned int reg;
 
@@ -123,7 +123,7 @@ int rk808_set_suspend_enable(struct regulator_dev *rdev)
 				  0);
 }
 
-int rk808_set_suspend_disable(struct regulator_dev *rdev)
+static int rk808_set_suspend_disable(struct regulator_dev *rdev)
 {
 	unsigned int reg;