clk: rockchip: handle critical clocks after registering all clocks

Currently the registration of critical clocks is done in the function
shared between rk3066 and rk3188 clock trees. That results in them
getting handled maybe before all of them are registered.

Therefore move the critical clock handling down to the end of the soc-
specific clock registration function, so that all clocks are registered
before they're maybe handled as critical clock.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Michael Niewoehner <linux@mniewoehner.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>