io_uring/rsrc: avoid NULL node check on io_sqe_buffer_register() failure

The done: label is only reachable if node is non-NULL. So don't bother
checking, just call io_free_node().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250228235916.670437-4-csander@purestorage.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>