power: supply: bq25980: remove redundant zero check on ret

Currently ret is assigned to zero and the following statement checks
if it is non-zero. This check is redundant and can be removed

Addresses-Coverity: ("Logically dead code")
Fixes: 5069185f ("power: supply: bq25980: Add support for the BQ259xx family")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>