power: suppy: ucs1002: Make the symbol 'ucs1002_regulator_enable' static

Fix the following sparse warning:

drivers/power/supply/ucs1002_power.c:492:5: warning: symbol 'ucs1002_regulator_enable' was not declared. Should it be static?

Fixes: a3d70dac ("power: suppy: ucs1002: disable power when max current is 0")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/ucs1002_power.c

@@ -489,7 +489,7 @@ static irqreturn_t ucs1002_alert_irq(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-int ucs1002_regulator_enable(struct regulator_dev *rdev)
+static int ucs1002_regulator_enable(struct regulator_dev *rdev)
 {
 	struct ucs1002_info *info = rdev_get_drvdata(rdev);