firewire: fw-ohci: disable PHY packet reception into AR context

We want the rcvPhyPkt bit in LinkControl off before we start using the
chip.  However, the spec says that the reset value of it is undefined.
Hence switch it explicitly off.

https://bugzilla.redhat.com/show_bug.cgi?id=244576#c48

 shows that for
example the nForce2 integrated FireWire controller seems to have it on
by default.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Jarod Wilson <jwilson@redhat.com>