power: twl4030: fix a missing check of return value

If twl4030_bci_read() fails, the read data in "s" is incorrect,
which is however used in the following execution. The fix checks
the return value of twl4030_bci_read() and returns an error code
upstream upon the failure of twl4030_bci_read().
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/twl4030_charger.c

@@ -809,7 +809,9 @@ static int twl4030_bci_get_property(struct power_supply *psy,
 		is_charging = state & TWL4030_MSTATEC_AC;
 	if (!is_charging) {
 		u8 s;
-		twl4030_bci_read(TWL4030_BCIMDEN, &s);
+		ret = twl4030_bci_read(TWL4030_BCIMDEN, &s);
+		if (ret < 0)
+			return ret;
 		if (psy->desc->type == POWER_SUPPLY_TYPE_USB)
 			is_charging = s & 1;
 		else