power: supply: bq25890_charger: fix incorrect error return when bq25890_field_read fails

Currently a read failure by bq25890_field_read on F_DEV_REV is returning
an error in id instead of rev. Fix this by returning the value in rev.

Addresses-Coverity: ("Copy-paste error")
Fixes: d20267c9a9 ("power: supply: bq25890_charger: Add support of BQ25892 and BQ25896 chips")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq25890_charger.c

@@ -765,7 +765,7 @@ static int bq25890_get_chip_version(struct bq25890_device *bq)
 	rev = bq25890_field_read(bq, F_DEV_REV);
 	if (rev < 0) {
 		dev_err(bq->dev, "Cannot read chip revision.\n");
-		return id;
+		return rev;
 	}
 
 	switch (id) {