Revert "ath9k: Parse DTIM period from mac80211"

Revert "ath9k: Parse DTIM period from mac80211"

This reverts commit a55d53994a07a44f72bd80b15eab8a150b5e20ee.

Event though with the above commit we obtain the configured DTIM period
from the AP rather than always hardcoding it to '1', this seems to cause
problems under the following scenarios:
* Preventing association with broken AP's
* Adds latency in roaming
So its better to always use the safe value of '1' for dtim period

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