qcacmn: Fix use after free for vdev

In existing code vdev is getting referenced after being
freed, during pdev detach while releasing tx descriptors.

Add code to drain tx descriptiors during vdev detach.

Change-Id: I2ea447d5d0a5be6539fddacb4b1c0b5f4601a71e
CRs-Fixed: 2203070
1 file changed