igc: check return value of ret_val in igc_config_fc_after_link_up

Check return value from ret_val to make error check actually work.

Fixes: 4eb80801 ("igc: Add setup link functionality")
Signed-off-by: NKevin Lo <kevlo@kevlo.org>
Acked-by: NSasha Neftin <sasha.neftin@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_mac.c

@@ -638,7 +638,7 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	}
 
 out:
-	return 0;
+	return ret_val;
 }
 
 /**