ath6kl: fix busy loop in ath6kl_bmi_get_rx_lkahd()

ath6kl: fix busy loop in ath6kl_bmi_get_rx_lkahd()

Brent reported that ath6kl busy loops if firmware doesn't boot for some
reason (in this case he was using an older firmware which wasn't supported
by ath6kl).

Investigation revealed that this was even on purpose,
ath6kl_bmi_get_rx_lkahd() had a parameter to disable the timeout check,
which is extremely evil. I didn't find any reason why the timeout needs
to be disabled so I just removed the feature. The function already busyloops
a maximum of one second if it doesn't get an answer, even that's too long.
If something takes longer than that a more friendly approach is needed.

Reported-by: Brent Taylor <btaylor1@motorolasolutions.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>