ieee1394: raw1394: Fix async send

While playing with libiec61883 I've noticed that async_send is broken
because it was doing copy_from_user(...., packet->data_size) before
packet->data_size was set to any useful value.  It got broken when
packet->allocated_data_size got introduced, as hpsb_alloc_packet does
not set packet->data_size anymore.  (Regression in 2.6.22-rc1)

Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>