buffered_file: unfold migrate_fd_close

We only used it once, just remove the callback indirection.

Signed-off-by: Juan Quintela <quintela@redhat.com>

migration.h

@@ -82,6 +82,7 @@ ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,
                               size_t size);
 void migrate_fd_put_ready(MigrationState *s);
 void migrate_fd_wait_for_unfreeze(MigrationState *s);
+int migrate_fd_close(MigrationState *s);
 
 void add_migration_state_change_notifier(Notifier *notify);
 void remove_migration_state_change_notifier(Notifier *notify);