LF-3751 usb: dwc3: core: set port cap dir to be device mode for disconnect

LF-3751 usb: dwc3: core: set port cap dir to be device mode for disconnect

If the dual role port does not connect to either host or device,
do not leave the port cap dir to be the value of last role, instead
we set it to be device mode, power measure test shows the power
will be high if leave the port cap dir register to be host mode
while the port is empty.

Reviewed-by: Ran Wang<ran.wang_1@nxp.com>
Signed-off-by: Li Jun <jun.li@nxp.com>