osmo_io: Avoid read of uninitialized variable

Change-Id: Ica8087c73fc10f01026fdbe692b172ad07fe593d
Fixes: CID#315618
diff --git a/src/core/osmo_io_poll.c b/src/core/osmo_io_poll.c
index 95aa84a..bc203c0 100644
--- a/src/core/osmo_io_poll.c
+++ b/src/core/osmo_io_poll.c
@@ -61,7 +61,7 @@
 		hdr.hdr.msg_iov = &hdr.iov[0];
 		hdr.hdr.msg_iovlen = 1;
 		hdr.hdr.msg_name = &hdr.osa.u.sa;
-		hdr.hdr.msg_namelen = osmo_sockaddr_size(&hdr.osa);
+		hdr.hdr.msg_namelen = sizeof(struct osmo_sockaddr);
 
 		rc = recvmsg(ofd->fd, &hdr.hdr, flags);
 		if (rc > 0)