qemu-options.hx: fix tls-channel help text

Remove the default compiled out tunnel channel, add the always available
cursor channel. Optimally the man page would depend on compiled in
options, but that's harder to do.

RHBZ: 688586
Acked-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NAlon Levy <alevy@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

qemu-options.hx

@@ -857,8 +857,8 @@ The x509 file names can also be configured individually.
 @item tls-ciphers=<list>
 Specify which ciphers to use.
 
-@item tls-channel=[main|display|inputs|record|playback|tunnel]
-@item plaintext-channel=[main|display|inputs|record|playback|tunnel]
+@item tls-channel=[main|display|cursor|inputs|record|playback]
+@item plaintext-channel=[main|display|cursor|inputs|record|playback]
 Force specific channel to be used with or without TLS encryption.  The
 options can be specified multiple times to configure multiple
 channels.  The special name "default" can be used to set the default