fuse: refactor duplicate queue teardown operation

fuse: refactor duplicate queue teardown operation

Extract common queue iteration and teardown logic into
fuse_uring_teardown_all_queues() helper function to eliminate code
duplication between fuse_uring_async_stop_queues() and
fuse_uring_stop_queues().

This is a pure refactoring with no functional changes, intended to
improve maintainability.

Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
Reviewed-by: Bernd Schubert <bernd@bsbernd.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>