of: Remove old and misplaced function declarations

The following functions don't exist:
  finish_device_tree()
  print_properties()
  prom_n_intr_cells()
  prom_get_irq_senses()

The following functions are in drivers/of/base.c, so the declaration
belongs in of.h instead of of_fdt.h
  of_machine_is_compatible()
  prom_add_property()
  prom_remove_property()
  prom_update_property()

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Michal Simek <monstr@monstr.eu>