io_uring/net: don't store send address ptr

For non "msg" requests we copy the address at the prep stage and there
is no need to store the address user pointer long term. Pass the SQE
into io_send_setup(), let it parse it, and remove struct io_sr_msg addr
addr_len fields. It saves some space and also less confusing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/db3dce544e17ca9d4b17d2506fbbac1da8a87824.1729607201.git.asml.silence@gmail.com


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