ARM: S5PV210: Add support CPUFREQ

This patch adds CPUFREQ driver for supporting DFS(Dynamic Frequency Scaling).
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>