ath10k: fix dma unmap direction for management frames

The management frames transmitted are dma mapped with
direction TO_DEVICE, but incorrectly mapped with
direction FROM_DEVICE during tx complete and error cases.

Fix the direction of dma during dma unmap of the
transmitted management frames.

Tested HW: WCN3990
Tested FW: WLAN.HL.2.0-01188-QCAHLSWMTPLZ-1

Fixes: 38a1390e ("ath10k: dma unmap mgmt tx buffer if wmi cmd send fails")
Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>