ath11k: add branch predictors in dp_tx path

Add branch prediction in dp_tx code path in tx and tx completion handlers.
Also in ath11k_dp_tx_complete_msdu , the pointer that is returned by
rcu_dereference() is not dereferenced. so it is preferable to use
rcu_access_pointer() here.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-01734-QCAHKSWPL_SILICONZ-1 v2

Co-developed-by: Sriram R <srirrama@codeaurora.org>
Signed-off-by: Sriram R <srirrama@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: P Praneesh <ppranees@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1630560820-21905-12-git-send-email-ppranees@codeaurora.org