usb: dwc3: xilinx: Add support for controller power state for host mode

commit  8ff0aafe648a3a7b4c2e2909f46ebf534015a476 from
https://github.com/Xilinx/linux-xlnx.git

 xlnx_rebase_v5.10

In dwc3 usb controller, power state switching from D0->D3 and D3->D0
support in device mode, not in host mode.
Added dr_mode host mode conditional checking in suspend and resume
functionality.
To get the unified dr_mode device node property from the child node of
dwc3, added usb get dr_mode functionality.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
State: pending
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>