wlan: Fix for HDD Tx Timeout in IBSS mode

The OS has only four queues, one per AC. The driver multiplexes
those queues in to multiple STA queues. Hence, when the station
leaves, the queue was getting disabled causing the OS backpressure.
This eventually causes OS to invoke HDD Tx timeout callback
registered by the driver.

Change-Id: I071f7da94e7b0f175fff47e1dfefac88ec0c7574
CRs-Fixed: 556369