ath10k: high latency fixes for beacon buffer

Beacon buffer for high latency devices does not use DMA. other similar
buffer allocation methods in the driver have already been modified for
high latency path. Fix the beacon buffer allocation left out in the
earlier high latency changes.

Signed-off-by: Alagu Sankar <alagusankar@silex-india.com>
Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
Patchwork-Id: 10906003
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>