ath10k: remove DMA mapping wrappers

There's no real benefit from using them. DMA-API
already provides debugging. Some skbuffs are
already mapped directly with DMA-API since wrapper
arguments were insufficient and extending them
would be pointless.

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