net: smsc911x: Fix runtime PM imbalance on error

[ Upstream commit 539d39ad0c61b35f69565a037d7586deaf6d6166 ]

Remove runtime PM usage counter decrement when the
increment function has not been called to keep the
counter balanced.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>