power: change from meaningless value to error number

'-1' is absolutely meaningless value.
This patch changed from meaningless value to error number.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/pmic/pmic_max77686.c b/drivers/power/pmic/pmic_max77686.c
index 93c8d2b..8e65331 100644
--- a/drivers/power/pmic/pmic_max77686.c
+++ b/drivers/power/pmic/pmic_max77686.c
@@ -67,14 +67,14 @@
 
 	if (ldo < 1 || ldo > 26) {
 		printf("%s: %d is wrong ldo number\n", __func__, ldo);
-		return -1;
+		return -EINVAL;
 	}
 
 	adr = MAX77686_REG_PMIC_LDO1CTRL1 + ldo - 1;
 	hex = max77686_ldo_volt2hex(ldo, uV);
 
 	if (!hex)
-		return -1;
+		return -EINVAL;
 
 	ret = pmic_reg_read(p, adr, &val);
 	if (ret)
@@ -120,7 +120,7 @@
 
 	if (ldo < 1 || 26 < ldo) {
 		printf("%s: %d is wrong ldo number\n", __func__, ldo);
-		return -1;
+		return -EINVAL;
 	}
 
 	adr = MAX77686_REG_PMIC_LDO1CTRL1 + ldo - 1;
@@ -161,7 +161,7 @@
 	if (mode == 0xff) {
 		printf("%s: %d is not supported on LDO%d\n",
 		       __func__, opmode, ldo);
-		return -1;
+		return -ENOTSUPP;
 	}
 
 	ret = pmic_reg_read(p, adr, &val);
@@ -182,7 +182,7 @@
 	size = ARRAY_SIZE(max77686_buck_addr);
 	if (buck >= size) {
 		printf("%s: %d is wrong buck number\n", __func__, buck);
-		return -1;
+		return -EINVAL;
 	}
 
 	adr = max77686_buck_addr[buck];
@@ -238,7 +238,7 @@
 	if (mode == 0xff) {
 		printf("%s: %d is not supported on BUCK%d\n",
 		       __func__, opmode, buck);
-		return -1;
+		return -ENOTSUPP;
 	}
 
 	ret = pmic_reg_read(p, adr, &val);
@@ -271,20 +271,20 @@
 	if (node < 0) {
 		debug("PMIC: No node for PMIC Chip in device tree\n");
 		debug("node = %d\n", node);
-		return -1;
+		return -ENODEV;
 	}
 
 	parent = fdt_parent_offset(blob, node);
 	if (parent < 0) {
 		debug("%s: Cannot find node parent\n", __func__);
-		return -1;
+		return -ENODEV;
 	}
 
 	/* tmp since p->bus is unsigned */
 	tmp = i2c_get_bus_num_fdt(parent);
 	if (tmp < 0) {
 		debug("%s: Cannot find I2C bus\n", __func__);
-		return -1;
+		return -ENODEV;
 	}
 	p->bus = tmp;
 	p->hw.i2c.addr = fdtdec_get_int(blob, node, "reg", 9);