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: Matthieu CASTET <castet.matthieu@free.fr>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 7116a1a..e265ba1 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -5660,7 +5660,8 @@
 
 	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)