firewire: cleanups

This patch contains the following cleanups:
- #if 0 the following unused structs:
  - fw-transaction.c:fw_low_memory_region
  - fw-transaction.c:fw_private_region
  - fw-transaction.c:fw_csr_region
  - fw-transaction.c:fw_unit_space_region
- remove the following unused EXPORT_SYMBOL's:
  - fw-card.c:fw_core_add_descriptor
  - fw-card.c:fw_core_remove_descriptor
  - fw-iso.c:fw_iso_context_create
  - fw-iso.c:fw_iso_context_destroy
  - fw-iso.c:fw_iso_context_start
  - fw-iso.c:fw_iso_context_queue
  - fw-iso.c:fw_iso_context_stop

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>