arm64: dts: rockchip: optimize clks for rk3399 dwc3

arm64: dts: rockchip: optimize clks for rk3399 dwc3

1. modify clock-names, according to Heiko's suggestion, clock names
should always be in the scope of the device block (named after what
it supplies), and clock-names are always meant from the perspective
of the individual ip-block.

2. remove unnecessary clocks, refer to rk3399 TRM, aclk_usb3 is the
parent of aclk_usb3otg0/1 and aclk_usb3_grf, and we will enable
aclk_usb3otg0/1 and aclk_usb3_grf, so don't need to enable aclk_usb3
again. In addition, the aclk_usb3_rksoc_axi_perf clk is used for usb3
performance monitor module which we don't use now, so don't need to
enable it.

Change-Id: I1d50a72d1523b8b70f1e5f388dc357807131dd7c
Signed-off-by: Wu Liang feng <wulf@rock-chips.com>