usb: mtu3: check capability of usb3 dual role

usb: mtu3: check capability of usb3 dual role

It is capable of supporting usb3 dual role if there is at least one
usb3 port for device and xhci controller, we can check it from the
controller's capability, so no need the property "mediatek,usb3-drd"
anymore, but I find the property is not decribed in dt-binding.
Meanwhile, also take into account if the u3 port is disabled when the
u3 phy is shared with pcie.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20220708071903.25752-4-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>