net: ethernet: ravb: Fix release of refclk

The call to clk_disable_unprepare() can happen before priv is
initialized. This means moving clk_disable_unprepare out of
out_release into a new label.

Fixes: 8ef7adc6 ("net: ethernet: ravb: Enable optional refclk")
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>