ath6kl: Recover from "wmi ctrl ep is full" condition

In some error conditions, fw pauses HTC pipes which would
result in control endpoint full condition. When we hit this
case, most of the time the device will be unusable. Re-initialize
the target to recover from this situation.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>