ath10k: wait for vdev delete response from firmware

When we add an interface immediately after removing
the interface the vdev deletion in firmware might not
have been completed. We need to synchronize the vdev creation
with the firmware.

Wait for vdev delete response from firmware when we
remove an interface.

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

Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>