clk: samsung: Change the return value of samsung_cmu_register_one()

This patch changes the return value of samsung_cmu_register_one()
from 'void' to 'samsung_clk_provider structure' pointer type because
samsung_clk_provider may be used in each clock driver.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>