ARM: EXYNOS: Add clock support for G-Scaler

Add required clock support for G-Scaler for exynos5

Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>