regulator: Storing tps65912 error codes in u8

get_ctrl_reg() returns -EINVAL so the error handling won't work here
if reg is a u8.

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/regulator/tps65912-regulator.c

···
 	struct tps65912_reg *pmic = rdev_get_drvdata(dev);
 	struct tps65912 *mfd = pmic->mfd;
 	int id = rdev_get_id(dev);
-	u8 reg;
+	int reg;
 
 	if (id < TPS65912_REG_DCDC1 || id > TPS65912_REG_LDO10)
 		return -EINVAL;