[BLUETOOTH]: Always send explicit hci_ll wake-up acks.

In the (rare) event of simultaneous mutual wake up requests,
do send the chip an explicit wake-up ack. This is required
for Texas Instruments's BRF6350 chip.

Signed-off-by: Ohad Ben-Cohen <ohad@bencohen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>