io_uring: move io_req_put_rsrc_nodes()

It'd be nice to hide details of how rsrc nodes are used by a request
from rsrc.c, specifically which request fields store them, and what bits
are signifying if there is a node in a request. It rather belong to
generic request handling, so move the helper to io_uring.c. While doing
so remove clearing of ->buf_node as it's controlled by REQ_F_BUF_NODE
and doesn't require zeroing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bb73fb42baf825edb39344365aff48cdfdd4c692.1746533789.git.asml.silence@gmail.com


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