ath: do not update cycle counters with sleep mode

When the chip is waking up from sleep state, the cycle counters
might have incorrect readings. So it is better not to update those
readings with software counters.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>