net: phy: smsc: add missed clk_disable_unprepare in smsc_phy_probe()

Add the missing clk_disable_unprepare() before return from
smsc_phy_probe() in the error handling case.

Fixes: bedd8d78 ("net: phy: smsc: LAN8710/20: add phy refclk in support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Link: https://lore.kernel.org/r/1605180239-1792-1-git-send-email-zhangchangzhong@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>