libertas: remove ps_supported flag, use fwcapinfo

Power save support depends on the firmware capabilities rather than the
card's hardware interface.  Use the FW_CAPINFO_PS bit in the firmware
capabilities mask throughout the driver in place of the redundant
ps_supported flag and don't make decisions about PS support in the
interface drivers (with the exception of a special case in the USB
driver).

V2: put the USB special case in the right place.

Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/libertas/wext.c b/drivers/net/wireless/libertas/wext.c
index 8bc19074..e96451c 100644
--- a/drivers/net/wireless/libertas/wext.c
+++ b/drivers/net/wireless/libertas/wext.c
@@ -712,7 +712,7 @@
 
 	lbs_deb_enter(LBS_DEB_WEXT);
 
-	if (!priv->ps_supported) {
+	if (!(priv->fwcapinfo & FW_CAPINFO_PS)) {
 		if (vwrq->disabled)
 			return 0;
 		else