ath6kl: cold reset target after host warm boot

Julien reported that ar6004 usb device fails to initialise
after host has been rebooted and power is still on for the ar6004 device. He
found out that doing a cold reset fixes the issue.

I wasn't sure what would be the best way to detect if target needs a reset so I
settled on checking a timeout from htc_wait_recv_ctrl_message().

Reported-by: Julien Massot <jmassot@aldebaran-robotics.com>
Tested-by: Julien Massot <jmassot@aldebaran-robotics.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>