clk: samsung: exynos3250: Use samsung_cmu_register_one() to simplify code

This patch uses the samsung_cmu_register_one() to simplify code
for Exynos3250.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>