vnc: fix tls-creds error message

The parameter is called 'tls-creds', 'credid' is just the
variable name in the code.
Signed-off-by: NWolfgang Bumiller <w.bumiller@proxmox.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 1452681360-29239-1-git-send-email-w.bumiller@proxmox.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

ui/vnc.c

@@ -3606,7 +3606,7 @@ void vnc_display_open(const char *id, Error **errp)
             qemu_opt_get(opts, "x509") ||
             qemu_opt_get(opts, "x509verify")) {
             error_setg(errp,
-                       "'credid' parameter is mutually exclusive with "
+                       "'tls-creds' parameter is mutually exclusive with "
                        "'tls', 'x509' and 'x509verify' parameters");
             goto fail;
         }