regulators: Add definition of regulator_set_voltage_time() for !CONFIG_REGULATOR

We already have dummy implementation for most of the regulators APIs for
!CONFIG_REGULATOR case and were missing it for regulator_set_voltage_time().

Found this issue while compiling cpufreq-cpu0 driver without regulators support
in kernel.

drivers/cpufreq/cpufreq-cpu0.c: In function ‘cpu0_cpufreq_probe’:
drivers/cpufreq/cpufreq-cpu0.c:186:3: error: implicit declaration of function ‘regulator_set_voltage_time’ [-Werror=implicit-function-declaration]

Fix this by adding dummy definition for regulator_set_voltage_time().
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/linux/regulator/consumer.h

@@ -397,6 +397,12 @@ static inline int regulator_set_voltage(struct regulator *regulator,
 	return 0;
 }
 
+static inline int regulator_set_voltage_time(struct regulator *regulator,
+					     int old_uV, int new_uV)
+{
+	return 0;
+}
+
 static inline int regulator_get_voltage(struct regulator *regulator)
 {
 	return -EINVAL;