clk: rockchip: release io resource when failing to init clk on rk3399

We should call iounmap to relase reg_base since it's not going
to be used any more if failing to init clk.

This was missing on the newly added rk3399 clock tree.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>