r8169: use pci_prepare_to_sleep in rtl_shutdown

Use pci_prepare_to_sleep() like PCI core does in pci_pm_suspend_noirq.
This aligns setting a low-power mode during shutdown with the handling
of the transition to system suspend. Also the transition to runtime
suspend uses pci_target_state() instead of setting D3hot unconditionally.

Note: pci_prepare_to_sleep() uses device_may_wakeup() to check whether
device may generate wakeup events. So we don't lose anything by
not passing tp->saved_wolopts any longer.

Signed-off-by: Heiner Kallweit <[e-mail]>
Reviewed-by: Jacob Keller <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/realtek/r8169_main.c

···
 	/* Restore original MAC address */
 	rtl_rar_set(tp, tp->dev->perm_addr);
 
-	if (system_state == SYSTEM_POWER_OFF && !tp->dash_enabled) {
-		pci_wake_from_d3(pdev, tp->saved_wolopts);
-		pci_set_power_state(pdev, PCI_D3hot);
-	}
+	if (system_state == SYSTEM_POWER_OFF && !tp->dash_enabled)
+		pci_prepare_to_sleep(pdev);
 }
 
 static void rtl_remove_one(struct pci_dev *pdev)