MIPS: SGI-IP27: Free some unused memory

platform_device_add_data() duplicates the memory it is passed. So we can
free some memory to save a few bytes that would remain unused otherwise.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>