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.

CRs-Fixed: 2065345
Change-Id: Id045087b03d5c5e6451f79b9c1177aca26ed34a2
Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>