console: add & use qemu_console_lookup_by_device_name

We have two places needing this, and a third one will come shortly.
So factor things out into a helper function to reduce code duplication.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
diff --git a/ui/input.c b/ui/input.c
index bdcb974..fce99ba 100644
--- a/ui/input.c
+++ b/ui/input.c
@@ -82,19 +82,12 @@
                              const char *device_id, int head,
                              Error **errp)
 {
-    DeviceState *dev;
     QemuConsole *con;
+    Error *err = NULL;
 
-    dev = qdev_find_recursive(sysbus_get_default(), device_id);
-    if (dev == NULL) {
-        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
-                  "Device '%s' not found", device_id);
-        return;
-    }
-
-    con = qemu_console_lookup_by_device(dev, head);
-    if (con == NULL) {
-        error_setg(errp, "Device %s is not bound to a QemuConsole", device_id);
+    con = qemu_console_lookup_by_device_name(device_id, head, &err);
+    if (err) {
+        error_propagate(errp, err);
         return;
     }