ieee1394: eth1394: contain host reset

Call only eth1394's own host reset handler from .tx_timeout, not the
reset hooks of all other IEEE 1394 drivers.

A minor drawback of this patch is that ether1394_host_reset by timeout
is not serialized against ether1394_host_reset by bus reset.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>