ARM: S5PV210: Add struct clk_ops for clk_fout_apll

Current fout_apll has fixed rate value. So CPUFREQ driver gets
incorrect value when finding current CPU frequency. Because some
operation level need to change APLL.
Added get_rate function for fout_apll can give correct frequency
value when calling get_rate function.

Signed-off-by: Jaecheol Lee <jc.lee@samsung.com>
Signed-off-by: Sangbeom Kim <sbkim73@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>