usb: dwc3: redo the mode setting at core init

usb: dwc3: redo the mode setting at core init

When dwc3 core enters into suspend mode, the PD may turn off
for power saving, which will cause dwc3 controller lost the
mode operation when resuming time.

This adds redo the mode setting into dwc3_core_init() function
to avoid this issue.

BUG=Redmine: Defect#110481
TEST=rk3399-sapphire-excavator-box(CVTE), check if USB3.0 HUB
can be enumerated after PM resume.

Change-Id: I61c512e9c368afc665cd4d5900367079ed22a34e
Signed-off-by: Frank Wang <frank.wang@rock-chips.com>