power: supply: mm8013: Fix an error checking issue in mm8013_checkdevice()

There is a missing "ret = " assignment so this checks the same "ret"
value twice.

Fixes: c75f4bf ("power: supply: Introduce MM8013 fuel gauge driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/c46b4408-bf1d-408d-9e6b-16b0ad272532@moroto.mountain
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Author: Dan Carpenter

drivers/power/supply/mm8013.c

@@ -53,7 +53,7 @@ static int mm8013_checkdevice(struct mm8013_chip *chip)
 	if (ret < 0)
 		return ret;
 
-	regmap_read(chip->regmap, REG_BATID, &val);
+	ret = regmap_read(chip->regmap, REG_BATID, &val);
 	if (ret < 0)
 		return ret;