selftests: mptcp: connect: fix build regression caused by backport

Since v6.1.154, mptcp selftests have failed to build with the following
errors:

mptcp_connect.c: In function ‘main_loop_s’:
mptcp_connect.c:1040:59: error: ‘winfo’ undeclared (first use in this function)
 1040 |                 err = copyfd_io(fd, remotesock, 1, true, &winfo);
      |                                                           ^~~~~
mptcp_connect.c:1040:59: note: each undeclared identifier is reported only once for each function it appears in
mptcp_connect.c:1040:23: error: too many arguments to function ‘copyfd_io’; expected 4, have 5
 1040 |                 err = copyfd_io(fd, remotesock, 1, true, &winfo);
      |                       ^~~~~~~~~                          ~~~~~~
mptcp_connect.c:845:12: note: declared here
  845 | static int copyfd_io(int infd, int peerfd, int outfd, bool close_peerfd)
      |            ^~~~~~~~~

This is caused by commit ff160500 ("selftests: mptcp: connect: catch
IO errors on listen side"), a backport of upstream 14e22b43,
which attempts to use the undeclared variable 'winfo' and passes too many
arguments to copyfd_io(). Both the winfo variable and the updated
copyfd_io() function were introduced in upstream
commit ca7ae891 ("selftests: mptcp: mptfo Initiator/Listener"),
which is not present in v6.1.y.

The goal of the backport is to stop on errors from copyfd_io.
Therefore, the backport does not depend on the changes in upstream
commit ca7ae891 ("selftests: mptcp: mptfo Initiator/Listener").

This commit simply removes ', &winfo' to fix a build failure.

Fixes: ff160500 ("selftests: mptcp: connect: catch IO errors on listen side")
Signed-off-by: Kenta Akagi <k@mgml.me>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>