io_uring/kbuf: open code __io_put_kbuf()

__io_put_kbuf() is a trivial wrapper, open code it into
__io_put_kbufs().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9dc17380272b48d56c95992c6f9eaacd5546e1d3.1738724373.git.asml.silence@gmail.com


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