`rte_eth_link_get_nowait` return value ignored — build fails with `-Werror` on DPDK 25.11+

[tarun-t]

In lib/ff_dpdk_if.c line 219, rte_eth_link_get_nowait() is called without checking its return value. DPDK 25.11 marks this function with warn_unused_result, causing a build failure under -Werror.

Fix:

-            rte_eth_link_get_nowait(portid, &link);
+            if (rte_eth_link_get_nowait(portid, &link) < 0)
+                link.link_status = 0;