clk: sunxi: Use common of_clk_init() function

Use common of_clk_init() function to initialize clocks.

Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Acked-by: Maxime Ripard <maxime.ripard@anandra.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>