clk: rockchip: add some critical clocks for rv1108 SoC

the bus/periph/nclk_ddrupctl/pclk_ddrmon/pclk_acodecphy/pclk_pmu
no driver to handle them,
Chip design requirements for these clock to always on.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>