clk: qcom: Do not drop device node twice

of_find_node_by_name() drops the reference to a passed device node.
It is not necessary to drop it again, and doing so may result in the
device node being released prematurely.

Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Fixes: ee15faff ("clk: qcom: common: Add API to register board clocks backwards compatibly")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>