ath10k: Correct the DMA direction for management tx buffers

ath10k: Correct the DMA direction for management tx buffers

The management packets, send to firmware via WMI, are
mapped using the direction DMA_TO_DEVICE. Currently in
case of wmi cleanup, these buffers are being unmapped
using an incorrect DMA direction. This can cause unwanted
behavior when the host driver is handling a restart
of the wlan firmware.

We might see a trace like below

[<ffffff8008098b18>] __dma_inv_area+0x28/0x58
[<ffffff8001176734>] ath10k_wmi_mgmt_tx_clean_up_pending+0x60/0xb0 [ath10k_core]
[<ffffff80088c7c50>] idr_for_each+0x78/0xe4
[<ffffff80011766a4>] ath10k_wmi_detach+0x4c/0x7c [ath10k_core]
[<ffffff8001163d7c>] ath10k_core_stop+0x58/0x68 [ath10k_core]
[<ffffff800114fb74>] ath10k_halt+0xec/0x13c [ath10k_core]
[<ffffff8001165110>] ath10k_core_restart+0x11c/0x1a8 [ath10k_core]
[<ffffff80080c36bc>] process_one_work+0x16c/0x31c

Fix the incorrect DMA direction during the wmi
management tx buffer cleanup.

Tested HW: WCN3990
Tested FW: WLAN.HL.3.1-00784-QCAHLSWMTPLZ-1

Fixes: f8b1062e685 ("ath10k: handle mgmt tx completion event")
Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>