buffered_file: unfold migrate_fd_put_ready

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

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

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

migration.h

@@ -80,6 +80,7 @@ void migrate_fd_connect(MigrationState *s);
 
 ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,
                               size_t size);
+void migrate_fd_put_ready(MigrationState *s);
 
 void add_migration_state_change_notifier(Notifier *notify);
 void remove_migration_state_change_notifier(Notifier *notify);