regulator: tps65218: Fix build warnings

rdev_get_id() returns an int. Convert rid to type int to avoid the
following warnings:
drivers/regulator/tps65218-regulator.c:132:10: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
drivers/regulator/tps65218-regulator.c:146:10: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]

Signed-off-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/regulator/tps65218-regulator.c

@@ -127,7 +127,7 @@ static int tps65218_pmic_set_voltage_sel(struct regulator_dev *dev,
 static int tps65218_pmic_enable(struct regulator_dev *dev)
 {
 	struct tps65218 *tps = rdev_get_drvdata(dev);
-	unsigned int rid = rdev_get_id(dev);
+	int rid = rdev_get_id(dev);
 
 	if (rid < TPS65218_DCDC_1 || rid > TPS65218_LDO_1)
 		return -EINVAL;
@@ -141,7 +141,7 @@ static int tps65218_pmic_enable(struct regulator_dev *dev)
 static int tps65218_pmic_disable(struct regulator_dev *dev)
 {
 	struct tps65218 *tps = rdev_get_drvdata(dev);
-	unsigned int rid = rdev_get_id(dev);
+	int rid = rdev_get_id(dev);
 
 	if (rid < TPS65218_DCDC_1 || rid > TPS65218_LDO_1)
 		return -EINVAL;