ieee1394: ieee1394_transactions needs sched.h

ieee1394: ieee1394_transactions needs sched.h

drivers/ieee1394/ieee1394_transactions.c fails for me if CONFIG_SMP=n

gcc complains:
  CC      drivers/ieee1394/ieee1394_transactions.o
drivers/ieee1394/ieee1394_transactions.c: In function 'hpsb_get_tlabel':
drivers/ieee1394/ieee1394_transactions.c:183: error:
'TASK_INTERRUPTIBLE' undeclared (first use in this function)
drivers/ieee1394/ieee1394_transactions.c:183: error: (Each undeclared
identifier is reported only once

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (added comment)