[ath] wake up the hardware from power-save before doing transmit completion checking.

This was being done in the pre-AR9380 case, but not for AR9380 and later.
When powersave in STA mode is enabled, this may have lead to the transmit
completion code doing this:

• call the task, which doesn't wake up the hardware
• complete the frames, which doesn't touch the hardware
• schedule pending frames on the hardware queue, which DOES touch the hardware, and this will be ignored

This would show up in the logs like this:

(with debugging enabled):
Nov 27 23:03:56 lovelace kernel: Q1[ 0] (nseg=1) (DS.V:0xfffffe011bd57300 DS.P:0x49b57300) I: 168cc117 L:00000000 F:0005
...
(in general, doesn't require debugging enabled):
Nov 27 23:03:56 lovelace kernel: ath_hal_reg_write: reg=0x00000804, val=0x49b57300, pm=2

That register is a EDMA TX FIFO register (queue 1), and the val is the descriptor
being written.

Whilst here, make sure the software queue gets kicked here.

Tested;

• AR9485, STA mode + powersave