xhci: really enqueue zero length TRBs.

Enqueue the first TRB even if full_len is zero.
Without this "adb install <apk>" freezes the system.
Signed-off-by: Alban Browaeys <alban.browaeys@gmail.com>
Fixes: 86065c27 ("xhci: don't rely on precalculated value of needed trbs in the enqueue loop")
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -3244,7 +3244,8 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	send_addr = addr;
 
 	/* Queue the TRBs, even if they are zero-length */
-	for (enqd_len = 0; enqd_len < full_len; enqd_len += trb_buff_len) {
+	for (enqd_len = 0; first_trb || enqd_len < full_len;
+			enqd_len += trb_buff_len) {
 		field = TRB_TYPE(TRB_NORMAL);
 
 		/* TRB buffer should not cross 64KB boundaries */