migration/multifd: Change retval of multifd_send_pages()

Using int is an overkill when there're only two options.  Change it to a
boolean.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240202102857.110210-18-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
1 file changed