clk: socfpga: fix refcount leak

The of_find_compatible_node() returns a node pointer with refcount
incremented, but there is the lack of use of the of_node_put() when
done. Add the missing of_node_put() to release the refcount.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Fixes: 5343325f ("clk: socfpga: add a clock driver for the Arria 10 platform")
Fixes: a30d27ed ("clk: socfpga: fix clock driver for 3.15")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>