e1000e: potentially incorrect return for e1000e_setup_fiber_serdes_link

In the unlikely event that e1000_poll_fiber_serdes_link_generic() is called
and it returns an error, the returned error code value is not propagated to
the caller of e1000e_setup_fiber_serdes_link().
Signed-off-by: NBruce Allan <bruce.w.allan@intel.com>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/mac.c

@@ -922,7 +922,7 @@ s32 e1000e_setup_fiber_serdes_link(struct e1000_hw *hw)
 		e_dbg("No signal detected\n");
 	}
 
-	return 0;
+	return ret_val;
 }
 
 /**