Optimize rk3399 clocktree by removing CLK_IGNORE_UNUSED of some clocks.

clocks will managered by usb:
- clk_usbphy0_480m_src
- clk_usbphy1_480m_src
- clk_usbphy_480m

clocks will be managered by pvtm:
- clk_pvtm_core_l
- clk_pvtm_core_b
- clk_pvtm_ddr

clocks will be managered by dfi:
- pclk_ddr_mon
- clk_dfimon0_timer
- clk_dfimon1_timer
- aclk_dcf
- pclk_dcf
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>