clk: rockchip: rk3288: make all niu clocks critical

NIU clocks are related to the interconnect and it's important to other blocks.
Since we don't have a driver to handle it, we should always enable it to avoid
casually close.

Make all of them critical,so that we don't have to each clock on its own
once things break.

Signed-off-by: Jacob Chen <jacob-chen@iotwrt.com>
[dropped the matching CLK_IGNORE_UNUSED flags]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>