ath10k: make WMI commands block by design

This will be necessary for further changes in
command submission scheme.

Once HTC is cleaned up WMI commands will finally
block.

This requires for SWBA to be processed in a
non-atomic context for now. Once other necessary
changes are in this will be reverted.

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