usb: dwc3: ep0: fix setup_packet_pending initialization

It just ocurred to me that dwc3 already gives a
really hint of when a setup packet is pending and
that's the SETUP_PENDING TRB Status for EP0 IRQs.

Fix setup_packet_pending initialization based on
that. While at that, also make sure the comment in
gadget.c matches what code is doing.

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/gadget.c

@@ -2230,8 +2230,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 	 *
 	 * Our suggested workaround is to follow the Disconnect
 	 * Event steps here, instead, based on a setup_packet_pending
-	 * flag. Such flag gets set whenever we have a XferNotReady
-	 * event on EP0 and gets cleared on XferComplete for the
+	 * flag. Such flag gets set whenever we have a SETUP_PENDING
+	 * status for EP0 TRBs and gets cleared on XferComplete for the
 	 * same endpoint.
 	 *
 	 * Refers to: