airo : allow supend with card without power management

Some airo card don't support power Management [1].
Don't abort suspend with those cards.

00:06.0 Network controller: AIRONET Wireless Communications PC4800 (rev 01)
        Flags: medium devsel, IRQ 17
        Memory at dffffe00 (32-bit, non-prefetchable) [size=128]
        I/O ports at d000 [size=128]
        I/O ports at cc00 [size=64]
        Kernel driver in use: airo
Signed-off-by: NMatthieu CASTET <castet.matthieu@free.fr>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/airo.c

@@ -5660,7 +5660,8 @@ static int airo_pci_suspend(struct pci_dev *pdev, pm_message_t state)
 
 	pci_enable_wake(pdev, pci_choose_state(pdev, state), 1);
 	pci_save_state(pdev);
-	return pci_set_power_state(pdev, pci_choose_state(pdev, state));
+	pci_set_power_state(pdev, pci_choose_state(pdev, state));
+	return 0;
 }
 
 static int airo_pci_resume(struct pci_dev *pdev)