ath9k: Fix ath9k prevents CPU to enter C3 states

The DMA latency issue is observed only in Intel pinetrail platforms
but in the driver we had a default PM-QOS value of 55. This caused
unnecessary power consumption and battery drain in other platforms.

Remove the pm-qos thing in the driver code and address the throughput
issue in Intel pinetrail platfroms in user space using any one of
the scripts in below links:

http://www.kernel.org/pub/linux/kernel/people/mcgrof/scripts/cpudmalatency.c
http://johannes.sipsolutions.net/files/netlatency.c.txt

More details can be found in the following bugzilla link:

https://bugzilla.kernel.org/show_bug.cgi?id=27532



This reverts the following commits:

	98c316e3
	4dc3530d
	10598c12

Signed-off-by: Mohammed Shafi Shajakhan <mshajakhan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>