power_supply: Fix race in power_supply_uevent

Commit 54d29ad33e3483bcc7ca433a21cf294854e5154a (Power Supply: fix race
in device_create) introduced a race in power_supply_uevent. Previously it
checked that power_supply is available by checking for dev->driver_data.
But now dev->driver_data is set before power_supply->dev is initialised.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index c444d6b..49215da 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -201,7 +201,7 @@
 
 	dev_dbg(dev, "uevent\n");
 
-	if (!psy) {
+	if (!psy || !psy->dev) {
 		dev_dbg(dev, "No power supply yet\n");
 		return ret;
 	}