usb: dwc3: core: Check maximum_speed SSP genXxY

The DWC_usb32 controller supports dual-lane SuperSpeed Plus. Check the
maximum_speed property for any limitation in the HW to initialize and
validate the maximum number of lanes and speed the device will operate.

Currently the controller has no visibility into the HW parameter to
determine the maximum number of lanes the HW supports. If the number of
lanes is not specified for SSP, then set the default rate to gen2x2 for
DWC_usb32 and gen2x1 for DWC_usb31.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/08d43f2a99198bed84895c272340449a6d03710e.1611106162.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>