This patch adds bypass uart cfgs for rk1808 USB 3.0 OTG
port. In addition, please note that it needs to set the
uart2 rx/tx io selection in the reg "BUS_GRF_IOFUNC_CON0"
bit 15:14.
Change-Id: I77ea461be299c0454f5caee1349110b6f2714c30
Signed-off-by: William Wu <william.wu@rock-chips.com>