driver:i2c:s3c24x0: fix clock init for hsi2c

Fix clock value initialisation for Exynos other than Exynos5 for hsi2c.

Signed-off-by: Piotr Wilczek <p.wilczek@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Heiko Schocher <hs@denx.de>