rt2x00: Fix sleep-while-atomic bug in powersaving code.

The generic powersaving code that determines after reception of a frame
whether the device should go back to sleep or whether is could stay
awake was calling rt2x00lib_config directly from RX tasklet context.
On a number of the devices this call can actually sleep, due to having
to confirm that the sleeping commands have been executed successfully.

Fix this by moving the call to rt2x00lib_config to a workqueue call.

This fixes bug https://bugzilla.redhat.com/show_bug.cgi?id=731672

Tested-by: Tomas Trnka <tomastrnka@gmx.com>
Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Cc: <stable@vger.kernel.org>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 2ec5c00..99ff12d 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -943,6 +943,7 @@
 	 * Powersaving work
 	 */
 	struct delayed_work autowakeup_work;
+	struct work_struct sleep_work;
 
 	/*
 	 * Data queue arrays for RX, TX, Beacon and ATIM.