ath10k: fix kernel panic while shutting down AP

Based on GFP flag given to DMA coherent allocation, the behaviour of
dma_free_coherent is changed. This behavioural diffrence is noticeable
in ARM platform. If DMA memory is allocated with GFP_KERNEL, free
coherent can not be called inside spin lock. This is causing kernel
crash in ARM platforms. Fix this by changing GFP flag to atomic.

This is most likely a regression from commit 64badcb6d645 ("ath10k: workaround
fw beaconing bug").

Cc: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: use bss_info as txpower source

This simply changes the source for txpower setup.
It does not make ath10k use different txpower
values for different vifs.

This will make it easier to implement chanctx in
ath10k in the future.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>