[PATCH -next] net: stmmac: fix missing unlock on error in stmmac_suspend()

[Yang Yingliang]

Add the missing unlock before return from stmmac_suspend()
in the error handling case.

Fixes: 5ec55823438e ("net: stmmac: add clocks management for gmac driver")
Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: Yang Yingliang <yangyingli...@huawei.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c 
b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 170296820af0..973bdf11e59d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5605,8 +5605,10 @@ int stmmac_suspend(struct device *dev)
                /* Disable clock in case of PWM is off */
                clk_disable_unprepare(priv->plat->clk_ptp_ref);
                ret = pm_runtime_force_suspend(dev);
-               if (ret)
+               if (ret) {
+                       mutex_unlock(&priv->lock);
                        return ret;
+               }
        }
 
        mutex_unlock(&priv->lock);
-- 
2.25.1