firewire: allocate broadcast channel in hardware

On OHCI 1.1 controllers, let the hardware allocate the broadcast channel
automatically.  This removes a theoretical race condition directly after
a bus reset where it could be possible to read the channel allocation
register with channel 31 still being unallocated.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

diff --cc drivers/firewire/core-card.c
Simple merge

diff --cc drivers/firewire/core-topology.c
Simple merge

diff --cc drivers/firewire/core.h
Simple merge

diff --cc drivers/firewire/ohci.c
Simple merge