io_uring/uring_cmd: correct io_uring_cmd_done() ret type

io_uring/uring_cmd: correct io_uring_cmd_done() ret type

io_uring_cmd_done() takes the result code for the CQE as a ssize_t ret
argument. However, the CQE res field is a s32 value, as is the argument
to io_req_set_res(). To clarify that only s32 values can be faithfully
represented without truncation, change io_uring_cmd_done()'s ret
argument type to s32.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250902012609.1513123-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>