clk: fix compile for OF && !COMMON_CLK

With commit 766e6a4e

 (clk: add DT clock binding support),
compiling with OF && !COMMON_CLK is broken.

Reported-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
Reported-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>