usb: dwc3: gadget: make use of No Response Update Transfer

No Response Update Transfer is a special type of
Update Transfer command which can be used whenever
we're not relying on XferNotReady to prepare
transfers. With this, we don't need to wait for
CMDACT to be cleared and issue further commands to
the endpoint straight away.

Let's start using this version to skip the long-ish
wait.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>