char: avoid chardevice direct access

frontends should avoid accessing CharDriver struct where possible

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1499342940-56739-6-git-send-email-anton.nefedov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/char/parallel.c b/hw/char/parallel.c
index 75a1a2f..055789f 100644
--- a/hw/char/parallel.c
+++ b/hw/char/parallel.c
@@ -513,7 +513,7 @@
     int base;
     uint8_t dummy;
 
-    if (!qemu_chr_fe_get_driver(&s->chr)) {
+    if (!qemu_chr_fe_backend_connected(&s->chr)) {
         error_setg(errp, "Can't create parallel device, empty char device");
         return;
     }