pata_arasan_cf: add missing clk_disable_unprepare() on error path

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

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>