Don't separate the status stage of the XHCI USB control transfers into

its own job because this breaks the simplified QEMU XHCI TRB parser,
which expects the complete USB control transfer as a series of back to
back TRBs. The old behaviour is kept under #ifdef in case this change
breaks enumeration of any USB devices.

PR:		212021
MFC after:	1 week

sys/dev/usb/controller/xhci.c

@@ -2221,7 +2221,11 @@ xhci_setup_generic_chain(struct usb_xfer *xfer)
 		 * Send a DATA1 message and invert the current
 		 * endpoint direction.
 		 */
+#ifdef XHCI_STEP_STATUS_STAGE
 		temp.step_td = (xfer->nframes != 0);
+#else
+		temp.step_td = 0;
+#endif
 		temp.direction = UE_GET_DIR(xfer->endpointno) ^ UE_DIR_IN;
 		temp.len = 0;
 		temp.pc = NULL;