power_supply: sysfs: Use power_supply_*() API for accessing function attrs

Replace direct calls to power supply function attributes with wrappers.
Wrappers provide safe access in case of unregistering the power
supply (e.g. by removing the driver). Replace:
 - get_property -> power_supply_get_property
 - set_property -> power_supply_set_property
 - property_is_writeable -> power_supply_property_is_writeable

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/power_supply_sysfs.c

@@ -76,7 +76,7 @@ static ssize_t power_supply_show_property(struct device *dev,
 	if (off == POWER_SUPPLY_PROP_TYPE) {
 		value.intval = psy->type;
 	} else {
-		ret = psy->get_property(psy, off, &value);
+		ret = power_supply_get_property(psy, off, &value);
 
 		if (ret < 0) {
 			if (ret == -ENODATA)
@@ -125,7 +125,7 @@ static ssize_t power_supply_store_property(struct device *dev,
 
 	value.intval = long_val;
 
-	ret = psy->set_property(psy, off, &value);
+	ret = power_supply_set_property(psy, off, &value);
 	if (ret < 0)
 		return ret;
 
@@ -223,7 +223,7 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj,
 
 		if (property == attrno) {
 			if (psy->property_is_writeable &&
-			    psy->property_is_writeable(psy, property) > 0)
+			    power_supply_property_is_writeable(psy, property) > 0)
 				mode |= S_IWUSR;
 
 			return mode;