xhci: Silence "xHCI xhci_drop_endpoint called with disabled ep ..." messages

When re-applying the configuration after a successful usb device reset,
xhci_discover_or_reset_device has already dropped the endpoints, and free-ed
the rings.

The endpoints already being dropped is expected, and should not lead to
warnings. Use the fact that the rings are also free-ed in this scenario to
detect this, and suppress the "xHCI xhci_drop_endpoint called with disabled
ep ..." message in this case.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

--
Changes in v2:
Move the ring check to only guard the xhci_warn, so as to avoid side-effects
in case we have a scenario where the rings are free-ed, but the endpoint is
not yet dropped.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>