ath6kl: Make fw error recovery configurable

Add a modparam to configure recovery. Recovery
from firmware error is disabled by default to debug
the actual issue further. To recovery from error,
modprobe ath6kl_core recovery_enable=1.

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