[SPARC64]: constify of_get_property return: arch/sparc64

arch/sparc64/kernel/central.c

arch/sparc64/kernel/chmc.c

arch/sparc64/kernel/ebus.c

arch/sparc64/kernel/irq.c

arch/sparc64/kernel/isa.c

arch/sparc64/kernel/of_device.c

arch/sparc64/kernel/pci_sun4v.c

arch/sparc64/kernel/prom.c

arch/sparc64/kernel/sbus.c

arch/sparc64/kernel/time.c

arch/sparc64/solaris/misc.c