clk: rockchip: rk3399: add pll up and down when change pll freq

clk: rockchip: rk3399: add pll up and down when change pll freq

set pll sequence:
	->set pll to slow mode or other plls
	->set pll down
	->set pll params
	->set pll up
	->wait pll lock status
	->set pll to normal mode

To slove the system error:
rockchip_rk3399_wait_pll_lock: timeout waiting for pll to lock
rockchip_rk3399_pll_set_params: pll update unsucessful,
				trying to restore old params

Change-Id: I62aecd9f292de5a3c7bcd8a87231785bf115159d
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>