io_uring: transform send/recvmsg() -ERESTARTSYS to -EINTR

commit 441cdbd5 upstream.

We should never return -ERESTARTSYS to userspace, transform it into
-EINTR.

Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>